Automatic focus control camera

ABSTRACT

An automatic focus control camera is provided having a lens driven by a motor. The lens can be driven to an in-focus position during an actual film exposure operation if the exposure time is relatively fast enough with regard to the movement of the lens. Alternatively, the lens can be stopped immediately preceding the actual film exposure operation depending upon the measured exposure parameters.

This is a division of patent application Ser. No. 764,742, filed on Aug.9, 1985, now U.S. Pat. No. 4,671,640.

FIELD OF THE INVENTION

The present invention relates to an automatic focus control camerahaving an arrangement for obtaining various information to provide anautomatic focus control and to adjust a lens of the camera to an infocus position automatically based on the obtained information.

DESCRIPTION OF THE PRIOR ART

There have been proposed many kinds of automatic focus control camerasof the above type. However. in the conventional autofocus cameras thereare still many problems to be solved. First, it is necessary to obtainreliable information for performing the automatic focus control. Second,it is necessary to provide a practical driving of a motor forpositioning the lens in the in focus position in response to theinformation. With respect to the second issue, it is necessary to movethe lens to the in focus position with a minimum loss based on theobtained data, to decrease the time for positioning the lens at in focusposition, to determine whether the lens is at the in focus position andto process the obtained information in case the obtained information isnot suitable for the lens attached to the camera. Third, it is requiredfrom the point of view of manufacturing the cameras how to perform thevarious adjustments of the camera during the manufacturing process toassure an accurate performance of the camera.

In studying the first problem, conventionally, there have been knownfocus adjusting devices in which the various informations are obtainedfor the automatic focus control by receiving light which has passedthrough an interchangeable lens and a diaphragm aperture opening. In thefocus control device of the above type, the necessary information cannot be obtained in case the minimum F Number of the interchangeable lensis not smaller than a limit minimum F Number required in the automaticfocus control device. Against this drawback, there has been proposedsuch an arrangement that the minimum F number of the usedinterchangeable lens is sent to the camera body then the focus detectionis inhibited if the sent minimum F number is greater than the limitminimum F number required in the device. However, there areinterchangeable lenses that has a minimum F number which is variedcorresponding to zooming and/or focusing. In case an interchangeablelens of the above type is used, the automatic focus control with beenabled or disabled depending on the change of the minimum F number ofthe lens corresponding to the state of the focusing or zooming, wherebythe user may be perplexed.

In studying the second problem, the conventional automatic focusdetection device has such problems as follows:

(1) The focus detection device can not obtain the necessary informationfor the automatic focus control from an inadequate condition of aphotographic object, such as a low contrast. As the countermeasureagainst this problem, one proposed device is so arranged that when thefocus detection is disabled for a lens position, the lens is forciblymoved by a predetermined length so as to seek whether or not there isanother lens position where the focus detection is made possible.However, in this arrangement, if there happen to occur a condition thatthe focus detection is disabled during the progress of the normalautomatic focus control, toward a just focus position hhe operation ofthe lens movement is inadvertently changed to the seeking operation fromthe normal focusing, whereby an unnecessary lens movement is interposedin the desired focus control.

(2) Another arrangement is to obtain the necessary informationrepeatedly. In this arrangement, if the information sequentially takenin the camera is erroneous due to movement of the camera, and theautomatic focus adjustment is performed in response to the erroneousinformation, the lens is unnecessarily moved to and fro.

(3) Generally it takes time before the necessary information becomesavailable in the lens control circuit after the light measurement of thephotographic object is made. Thus, in a system in which the focusdetection is made during the lens movement, an error occurs between thelens position at which the light measurement is made and the lensposition at which the information used in the lens control circuitbecomes available, due to the lens movement during the internal time. Inorder to compensate for this error, conventionally a correction of theinformation taken is made by means of amending the information with aconstant value corresponding to the lens movement during the intervaltime. However, it takes a certain amount of time before the lensmovement reaches a stable speed in the beginning of the lens movement.Accordingly the amount of the lens movement during the time with thestable speed and the amount thereof under the unstable speed aredifferent, whereby an accurate focus control can not be expected if theinformation for the focus control is amended by the constant value asemployed in the prior art.

(4) In the process of the focus control, conventionally, the motor isdecelerated when the lens reaches a predetermined position near the infocus position to achieve a smooth stop of the lens movement. However,if the motor speed is different at the position at which thedeceleration begins, the length of lens movement from the beginning ofthe deceleration till the deceleration to a desired low speed of lensdiffers. In fact the lens may reach the near focus position with astable high speed or may reach the near focus position directly afterthe lens begins to move with a relatively low speed. Therefore, if thedeceleration of the motor is inadequately made to increase the time forlow speed lens movement, the rapid focus control can not be expected.

(5) As has been stated above, it is essential to decelerate the lens inthe near focus condition to prepare the smooth stop of the lensmovement. In case the focus control is performed when the object itselfis moving to and fro, however, there may occur the near focus conditionand the far focus condition alternatingly due to the movement of theobject to correspondingly change the speed of lens movement. If the lensis moved with a high speed or low speed alternatingly corresponding tothe near focus and far focus conditions, the smooth movement of the lensmay be deteriorated.

(6) Conventionally, it is employed to determine whether or not the lensis positioned in the in focus position by detecting that the lens issituated in a predetermined allowable range which is regarded as the infocus position. However, still a problem exists in determining how todecide the allowable range.

(7) It is strongly desired to position the lens in the in focus positionrapidly. However, the conventional automatic focus control is still notenough in complying with the above requirement.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an automatic focuscontrol camera which is able to complete the focus control rapidly witha smooth movement of the lens.

Another object of the present invention is to provide an automatic focuscontrol camera which is able to perform an accurate focus control.

A further object of the present invention is to provide an automaticfocus control camers which is enabled to move the lens based on the bestpossible information without any undesired movement.

A still further object of the present invention is to provide anautomatic focus control camera which is able to effect a smooth lenscontrol even if a photographic object is moving.

A still further object of the present invention is to provide anautomatic focus control camera with an improved operativity in theactual use.

According to a feature aspect of the present invention, in an automaticfocus control camera capable of obtaining a focus control informationduring focus adjustment comprising focus control information obtainingmeans requiring a time between the sensing of the focus condition andthe generation of data indicative of the necessary degree of focusadjustment, and modifying means for modifying the data with a degree offocus adjustment expected to occur with a predetermined speed during thetime, there is provided means for interrupting the operation of theobtaining means and the modifying means for a period beginning from theinitiation of focus adjustment. By this arrangement, at the initialstate of the focus adjustment, an erroneous focus adjustment due towrong modification of the data can be prevented and the modificationmeans can be effectively used.

According to another feature of the present invention, in an automaticfocus control camera in which when the remainder obtainable bysubtracting actual degree of focus adjustment from the necessary degreeof focus adjustment is less than a reference data, the driving power isreduced, the reference data can be changed corresponding to thenecessary degree of focus adjustment. Accordingly, in case the remainderis made small before the speed of the focus adjustment becomes highsince the necessary degree of focus adjustment is small, the referencedata is made small so that the power reduction may be made at a positionnearer the in focus position. By this arrangement, it can be avoided theproblem that it would take a long time for the focus adjustment due toany unnecessary early reduction of the power to the motor.

According to a further feature of the present invention, in an automaticfocus camera in which the driving power for moving the lens is reducedwhen the degree of the defocus becomes less than a reference level, thereference level is changed from a first reference level to a secondreference level which is greater than the first reference level when thedriving power is once reduced, whereby once the driving power isreduced, even if the degree of the defocus becomes large again due tothe movement of the photographic object, the reduction of the drivingpower is continued so that a smooth focus adjustment can be assured.

According to a further feature of the present invention, in an automaticfocus control camera in which the information for the focus control isnot reliable, a search for another focusing position at which a reliablefocus information is obtainable, there is further provided a disablingmeans for disabling the search operation even if it is suddenly decidedthat the information is unreliable when the focus adjustment is beingpracticed toward the in focus position. By this arrangement, undue focusadjustment can be prevented during the process of the focus adjustmentto the in focus position.

According to a further feature of the present invention, there isprovided a causing means for effecting the focus adjustment based on newinformation when an abrupt change between the successively obtainedinformation occurs due to such as a camera shake without responding tothe abruptly changing information. By this arrangement, an unnecessaryfocus adjustment due to the abrupt change of the information can beprevented.

According to a further feature of the present invention, when ateleconverter is used, a range of permissible defocusing which can bedealt with as in focus condition may be expanded compared to the casewhen the teleconverter is not used. In general, when the teleconverteris used, even if an object situated at the same distance moves the samedistance in the direction of the optical axis, the amount of change ofthe defocusing degree may be large compared to the case when theteleconverter is used. Also, when the teleconverter is used, theeffective F number changes to increase the depth of focus compared tothe case when the teleconverter is not used. Considering the abovematters, by expanding the range of permissible defocusing degree withthe presence of the teleconverter a reasonable decision on the focus canbe made.

According to a further feature of the present invention, focusadjustment is continued until the actual exposure to the film isinitiated even after the operation of the exposure is set. By thisarrangement, the time available for the focus control can be extendedcompared to the conventional arrangement in which the focus adjustmentis stopped when the operation of the exposure is set about even if thetime length between the initiation of the focus adjustment and actualexposure to the film is the same, thereby enabling a more suitable focusadjustment. In other words, the time from the completion of a suitablefocus adjustment till the actual exposure to the film can be shortened.

According to a further feature of the present invention, in a camera inwhich, the information obtaining function is prohibited, when theminimum aperture value of the interchangeable objective lens is greaterthan a limit, in case the effective aperture value of theinterchangeable lens with the diaphragm aperture fully open changes dueto zooming or focusing, said interchangeable lens is provided with meansfor outputting, independently from the actual variation of the effectivefully open aperture value, a signal indicative of the minimum of thevariable effective aperture value with the the diaphragm aperture fullyopen. In case such interchangeable lens is used, since it is completelyprohibited to obtain the information for focus control when the signalis greater then the limit, it can be prevented to confuse the user witha change between the enabled and disabled conditions of the automaticfocus control in the process of using the camera.

Ac cording to a further feature of the present invention, in a camera inwhich means for obtaining an information of focus condition iscontrolled by sequence control means for controlling the total cameraoperation sequence, said obtaining means can be pontrolled without saidsequence control means by selecting a possible operation mode. By thisarrangement, the obtaining means can be enabled in the manufacturingprocess for its adjustment, so that a disadvantage that the obtainingmeans of the camera can not be adjusted until the sequence control meansis mounted in the camera is eliminated. In addition after the camera isentered in the market, the operation of the obtaining means can beadjusted or inspected independent of the total camera operationsequence.

According to a further feature of the present invention, in a cameracomprising means for providing driving power corresponding to theinformation for focus control and means for informing said informationsensibly, whereby the automatic focus control mode in which theproviding means is operative and the manual focus control mode in whichthe providing means is inoperative can be selected as desired, under themanual focus control mode, the sensibly information means is enabled bymanipulating either a manually operable member for a shutter releaseoperation or another manually operable member for the exposureinformation setting, and under the automatic focus control mode, saidproviding means can be enabled only when the manually operable memberfor the shutter release operation is manipulated. The manual focuscontrol can be performed by a manual focus adjustment in associationwith information obtained by the sensibly informing means. Therefore, itis desired that the sensibly informing means is already enabled when theuser of the camera wishes to perform the manual focus control. By thearrangement as described above, since the sensibly informing means isalready enabled by the manipulation of the manually operable member forthe exposure information setting which is expected to be practiced priorto the focus adjustment, the user of the camera directly can perform thefocus adjustment without a further operation for enabling the sensiblyinforming means by means of the manipulation of the manually operablemember for the shutter release operation. On the other hand, under theautomatic focus control mode, it is desired to begin the automatic focusadjustment when the user of the camera sets the shutter releaseoperation. On the contrary, if the automatic focus adjustment beginsupon the exposure information setting, the user of the camera may beconfused. According to the feature of the invention said providing meanscan not be enabled by the manipulation of the manually operable memberfor the exposure information setting so that the confusion describedabove can be effectively prevented.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 comprised of FIGS. 1(A) and 1(B) is a schematic diagram showing acircuit arrangement of an automatic focus control camera according tothe present invention,

FIGS. 2(A)-2(H) and 3(A)-3(E) are flow charts showing the operation ofthe circuit arrangement shown in FIG. 1,

FIGS. 4(A) and 4(B) are a schematic diagram showing the details ofblocks LEC and COV of the automatic focus control circuit shown in FIG.1,

FIG. 5 is a schematic diagram showing the circuit relating tomicrocomputer MC₂ of FIG. 1 when it is operated independently frommicrocomputer MC₁ and

FIGS. 6(A)-6(E), 7(A)-7(F), 8(A)-8(G), 9(A)-9(F), 10(A)-10(D), and11(A)-11(D) are flow charts showing the operation of microcomputer MC₂in association with FIGS. 1 and 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a circuit diagram showing a whole camera system according tothe present invention. In the FIG. 1, BA denotes a D.C. power battery,the driving power is supplied through a driving power line +E to amicrocomputer MC₁ for controlling, a microcomputer MC₂ for detecting andadjusting a focal distance (the microcomputer MC₂ is called the AFmicrocomputer in the following), a display unit DSP, a buffer circuitBF, NOR gates NO₀, NO₁, a NAND gate NA₁, respective pull up resistersfor pulling up for switches S₁ , S₂ , S₃, TSS, ASS, ISS, MOSS, UPS, POS.

S₁ denotes a switch for measuring a brightness of an object, which isclosed when a shutter release button (not shown) of the camera is pusheddown to a first depth. When the switch S₁ is closed, the output of theNOR gate NO₁ goes down to "Low" and the operation of the microcomputerMC₁ for controlling is set about after an interrupt signal is inputtedto an interrupt terminal it₀ in the microcomputer MC₁. The switch TSS isclosed when an exposure time is changed. (The switch TSS is called theTv switch in the following.) The switch ASS is closed when an effectiveaperture value is changed. (The switch ASS is called the Av switch inthe following.) The switch ISS is closed when a sensitivity ISO of aused film is changed. (The switch ISS is called the Sv switch in thefollowing.) The switch MOSS is closed when an exposure control mode ischanged. (The switch MOSS is called the mode switch in the following.)When these switches TSS, ASS, ISS and MOSS are closed, an output of aNOR gate NO₁ goes down to "Low", whereby an output of the NOR gate N0₁down to "Low", and the interrupt signal is also inputted to theinterrupt terminal it₀ of the microcomputer MC₁ and the operation of themicrocomputer MC₁ is set about. UPS is a switch for increasing data.(The switch UPS is called the UP switch in the following.) DOS is aswitch for decreasing data. (The switch DOS is called the DOWN switch inthe following.) S₂ is a release switch which is closed when the shutterbutton is pushed down to a second depth which is deeper than the firstdepth. S₄ is a reset switch, which is changed over to a terminal EEafter the exposure controlling operation is completed. Said switch S₄ ischanged over to a terminal WE after charging in an exposure control modeis completed.

FIGS. 2 and 3 are flow charts showing the operation of the microcomputerMC₁. In the following, referring to FIGS. 2 and 3, the operation of thecamera system in FIG. 1 will be described. When the driving power issupplied through the driving power line +E after the battery BA ismounted in the camera, the microcomputer MC₁ is set about from the step#100 in FIG. 3. First of all, at the step #100 ports P₂₂, P₂₃, P₂₆, P₂₉and P₃₁ -P₄₀ of the microcomputer MC₁ are designated as an input mode,and at from the step #101 ports P₂₀, P₂₁, P₂₄, P₂₅, P₂₇, P₂₈, P₃₀, P₄₁,P₄₂ and P₄₃ are designated as an output mode. The ports P₂₀, P₂₁, P₂₄,P₃₀ , P₄₁, P₄₂ and P₄₃ designated as the output mode are initialized"High". On the other hand, the ports P₂₅, P₂₇ and P₂₈ designated as theoutput mode are initialized "Low". The microcomputer MC₁ acts to stopthe generation of reference clock pulses STCL from a terminal STCLOU.Then a flag CDFF is reset and a mode register MOR is set by "0". Theflag CDFF is set to "1" when a computation of the exposure control valueis completed. Under this state, the content of the register MOR is setby the data designating the exposure control mode, wherein "0"designates a program exposure control mode (referred to as a P mode inthe following), "3" designates an automatic control mode of adjustingthe effective aperture value with an exposure time priority (referred toas a S mode in the following), "2" designates an automatic control modeof the exposure time with adjusting the effective aperture valuepriority (referred to as a A mode in the following), "1" designates amanual setting mode of adjusting the effective aperture value and theexposure time (referred to as a M mode in the following). Next, at thestep #107, the data of the film sensitivity ISO 100 (Sv=5) is set in aregister for film sensitivity data TSR, then the data of F5.6 (Av=5) isset as a setting effective exposure value Avs at the step #108 and thedata of 1/60 sec (Tv=6) is set as a setting exposure time Tvs at thestep #109. At the step #110, it is displayed in the display unit DSPthat the exposure mode is the P mode and the film sensitivity is ISO100, the display of the effective aperture value and the exposure timeare blanked, and the operation of the microcomputer MC₁ is stopped afterit is inhibited for counters in the microcomputers to interrupt aninterruption permission signal is inputted to the interrupt terminalit₀.

When one of the switch S₁ for measuring the brightness of the object,the Tv switch TSS, the Av switch ASS, the Sv switch ISS and the modeswitch MOSS is closed, the microcomputer MC₁ is set about from the step#0 in FIG. 2 after the interrupt signal is inputted to the terminal it₀in the microcomputer MC₁. At the step #0, the driving power is suppliedfrom the driving power line +V after making the terminal P₃₀ "Low" atransistor BT₀ is turned on through the output of the buffer circuit BF.Next, the reference clock pulses are outputted from the terminal STCLOUto the AF computer , an interface circuit INF and a motor controlcircuit MCC. At the step #2, the content of a counter for the counterinterruption in the microcomputer MC₁ is reset and the counterinterruption is permitted, then at the step #3 the data of theexchangeable lens mounted in the camera is taken in.

Referring to FIG. 4, a way of reading data of the mounted lens will beexplained. In the lower part of the left hand side of FIG. 1, a blocksurrounded by one dashed chain line is the circuit diagram provided inthe exchangeable lens, wherein COV is a converter circuit for use insuch as a teleconverter lens arranged between the body of the camera andthe exchangeable lens. One example of these circuits are shown in FIG.4. When the microcomputer MC₁ reads the data of the lens, the terminalP₂₈ is made "Low" and the microcomputer MC₁ cancels the reset conditionof counters CO₀, CO₁, CO₂, CO₃ and T type flip flop TF₀, TF₅. Next, thecomputer MC₁ performs the input and output operation in series. that is,the eight pulses of the serial clock SICK are outputted from theterminal SICK₁, the counters CO₀ and CO₂ count the said clock pulsesthrough the inverter IN₀ and IN₁. Decoders DE₀, DE₂ make "High"terminals d₀ -d₇ in turn and make respective AND gates AG₀ -AG₇ and AG₁₀-AG₁₇ enable state, then the decoders DE₀, DE₂ output the data outputtedfrom ROMs RO₀ and RO₁ in series in turn from the lowest bit through ORgates OG₀, OG₂. The Q outputs of the respective T type flip flops TF₀and TF₅ become "High" at the positive edge of the eighth clock pulse (atthe negative edge in the output of the inverter) after terminals b₂ ofthe counters CO₀ and CO₂ goes down to "Low". After that. the Q outputsof the T type flip flops TF₀ and TF₅ become "Low" at the positive edgeof the next clock pulse. Then the counter CO₁ counts the said negativeedge of the Q output of the flip flop TF₀.

                  TABLE 1                                                         ______________________________________                                        b.sub.7                                                                           b.sub.6                                                                             b.sub.5                                                                             g.sub.3                                                                           g.sub.2                                                                           g.sub.1                                                                           g.sub.0                                                                           Address                                                                              Data                                   ______________________________________                                        0   0     0     0   0   0   0   00H    Check data                             0   0     1     0   0   0   1   01H    Minimum F number                                                              Avo                                    0   1     0     0   0   1   0   02H    Maximum effective                                                             aperture value Avmax                   0   1     1     0   0   1   1   03H    Minimum F number                                                              AFAvo for the AF                                                              operation                              1   0     0     0   1   0   0   04H    Eclipse data 00H                       1   0     1     1   0   0   0   000*****                                                                             Conversion factor kL                   1   1     0     1   0   0   1   001*****                                                                             Focal length fv                        1   1     1     1   0   1   0   010*****                                                                             Changed in aperture                                                           value according to                                                            zooming dAv                            ______________________________________                                         *****Output of zoom code plate                                           

                  TABLE 2                                                         ______________________________________                                        b.sub.7                                                                           b.sub.6                                                                             b.sub.5                                                                             e.sub.1                                                                           e.sub.0                                                                           Address                                                                              Data  Output data                              ______________________________________                                        0   0     0     0   1   80H    *     Check data                               0   0     1     0   1   81H    *     Avo                                      0   1     0     0   1   82H    *     Avmax                                    0   1     1     1   0   83H    80H + AFAvo + 80H + dAvc                                                      dAvc                                           1   0     0     1   0   84H    Avoc  Avoc                                     1   0     1     1   0   85H    kC    kL + kC → kL                      1   1     0     1   0   86H    fvc   fv + fvc → fv                     1   1     1     1   0   87H    dAvc  dAv + dAvc → dAv                  ______________________________________                                         *The data are transferred from the lens to the body of the camera.       

                  TABLE 3                                                         ______________________________________                                        b.sub.7                                                                             b.sub.6    b.sub.5                                                                             Address     Data                                       ______________________________________                                        0     0          0     00H         Check data                                 0     0          1     01H         Avo                                        0     1          0     02H         Avmax                                      0     1          1     03H         AFAvo                                      1     0          0     04H         00H                                        1     0          1     05H         kL                                         1     1          0     06H         fv                                         1     1          1     07H         00H                                        ______________________________________                                    

Table 1 shows the correlation between the outputs of the counter CO₃ andthe decoder DE₃ and the address and data of ROM RO₁ in a lens circuit LEin case the interchangeable objective lens is a zoom lens. Table 2 showsthe correlation between the outputs of the counter CO₁ and the decoderDE₁ and the address and data of ROM RO₀ in the converter lens COV.

Table 3 shows the relation between the address and the data in case theinterchangeable objective lens is a lens with a fixed focal length incomparison with Table 1.

In Tables 1, 2 and 3, the check data is the common data in all kinds ofthe lens to be mounted to the camera, which is used for checking whetheror not the interchangeable objective lens suitable for the system of thepresent embodiment is mounted properly to the body of the camera. Avo isa fully open aperture value at the shortest focal length (which is thesmallest fully open aperture value) in case the used interchangeableobjective lens is a zoom lens which changes the effective aperture valuecorresponding to the change in focal length, and Avo is also a fixedfully open aperture value in case the interchangeable objective lens isa lens such as a lens with a fixed focal length or a zoom lens, whichdoes not change the effective aperture value according to the change infocal length. Avmax is the maximum effective aperture value, which isthe fixed maximum effective aperture value or the maximum effectiveaperture value at the shortest focal length, similarly in the case ofthe fully open aperture value. When the lens is mounted on the camerathrough the converter lens COV, the three data are directly transferredto the camera because the data are outputted through the AND gate AN₂and the OR gate OR₁. In Table 2, "address" and "data" represent theaddress and the data in the ROM of the converter lens COV, and "outputdata" represents the data transmitted to the camera body from theconverter lens COV.

AFAvo is the minimum F number relating to the detection of aninformation for automatic focal control through the lens and itsdiaphragm. AFAvo is identical with Avo when the interchangeableobjective lens is a lens with a fixed focal length or a zoom lens withits effective aperture value unchangeable in response to the zooming.And AFAvo corresponds to a fully open aperture value at the longestfocal distance (which is the greatest fully open aperture value) in casethe interchangeable objective lens is a zoom lens which changes theeffective aperture value in accordance with the zooming. Moreover, AFAvocorresponds to the greatest fully open aperture value in case theinterchangeable objective lens is a lens which changes the effectiveaperture value in accordance with the focusing. The data of AFAvo isoutputted after it is added to the data 80H+dAvc from the ROM RO₀ in theconverter lens COV in the serial addition circuit ARC if the converterlens COV is used. dAvc means the change in the effective aperture valuecaused by using the converter lens COV, 80H represents that theconverter lens COV is mounted by the data "1" in the most significantbit of the one byte data.

Next, 00H is outputted from the ROM RO₁ in the lens LE and Avoc isoutputted from the ROM RO₁ in the converter lens COV, both as an eclipsedata. The eclipse data means a threshold value of the effective aperturevalue that the incident light to the body of the camera through the lensis eclipsed by the converter lens COV when the converter lens COV isarranged between the interchangeable objective lens and the body of thecamera. Therefore, when the converter lens COV is mounted, the botheclipse data are added and the eclipse data Avoc, which is the sum ofthe addition, is inputted to a circuit arranged in the body of thecamera. In case the converter lens COV is not mounted, the data 00Houtputted from the lens circuit LE is inputted to the circuit in thebody of the camera. A conversion factor kL predetermined in the usedlens is outputted from the ROM RO₁ in the used lens, which means theconversion factor to convert from a defocused quantity of the lenscalculated by the AF microcomputer MC₂ to the the number of the rotationof the AF motor for controlling a position of the optical system for theautomatic focus adjustment. The defocused quantity is representative ofthe difference between the position of the image of an object to befocused and a surface to which the image should be in focus. Thedefocused quantity is measured by a focus detecting device provided inthe body of the camera. The degree of the rotation of the AF motor (themotor for automatic focus control) necessary to reduce the defocusingquantity to zero by means of the focus adjustment caused by the AF motoris different in each interchangeable objective lens. The factor used inconversion of the defocusing quantity into the degree of the rotation ofthe AF motor is referred to as the conversion factor. As the data of theconversion factor kL changes in accordance with the focal length in azoom lens, the data representing the conversion factor kL is obtained atan address of RO₁ designated by a zoom code plate FCP. The data of theconversion factor kL is added to a conversion factor kC for theconverter lens COV outputted from the ROM RO₀, then the added data issent to the circuit in the body of the camera. Each of the data for kLand kC consists of a significant figure and an exponent part, the datain said each part are added respectively in the above addition in theconverter lens COV. Then the data are converted to the value kL indecimal system, and the calculation of kL×kB (wherein kB represents theconversion factor relating to the body of the camera) is performed toobtain the conversion factor k relating to the whole camera system inthe AF microcomputer Mc₂.

The data fv of the focal length (which is manually set when theinterchangeable objective lens is a zoom lens. or fixed when theinterchangeable objective lens is a lens with a fixed focal length) isoutputted from the RO₁ which is transmitted to the converter lens COV,then the data fv is added to data fvc which is a change in the focallength fv caused by the mounting of the converter lens COV, and theadded data is outputted to the circuit in the body of the camera. Thedata dAv which is the difference between the effective aperture value atthe shortest focal length and the effective aperture value at the setfocal length (in case of a zoom lens) is outputted from the RO₁, whichis transmitted to the circuit in the converter lens COV, then the datadAv is added to the data dAvc which is the change in aperture value ofthe interchangeable objective lens caused by the use of the converterlens COV, and the added data is inputted to the circuit in the body ofthe camera. In the body of the camera, the value of Avo+dAv+dAvc is setas the effective fully open aperture value in the whole optical system,and the value of Avmax+dAv is set as the maximum effective aperturevalue. In case the converter lens COV is not arranged, dAvc=0. In case azoom lens which does not change the effective aperture value in zooming,dAv=0.

In the flow chart shown in FIG. 2, after the input operation of the lensdata is completed, at the step #4, it is determined whether the switchS₁ for measuring the brightness is closed or not. In case the switch S₁is closed, the program flow goes to step #6, on the other hand, in casethe switch S₁ is open, the program flow goes to step #5. At the step #5,it is determined whether the performing mode is an AF mode (automaticfocus control mode) or a FA mode (focus aid mode in which the focusadjustment is manually made with the aid of the focus detection signal)by detecting the input level to the terminal P₂₉. In case the performingmode is the AF mode, the program flow goes to the step #6, on the otherhand, in case it is the AF mode, the program flow goes to the step #12.The determination of the AF mode or the FA mode is performed by way ofthe following operation, that is, the FA mode is performed and AF modeis not performed when the switches TSS, ASS, ISS, MOSS, UPS and DOSexcept the switch S₁ for measuring the brightness of the object areclosed and the microcomputer for controlling MC₁ begins to be operated.

At the step #6, it is determined whether the check data is inputted fromthe circuit in the lens LE, in case the check data is not inputted, theoperation of the AF mode or the FA mode is not performed because thelens is not mounted, then the program flow goes to the step #12. In casethe check data is inputted, the program flow goes to the step #7, thenAFAvo or AFAvo+dAvc is compared with the effective aperture thresholdvalue for calculating the defocusing quantity for the AF mode or the FAmode, that is, it is determined whether the value of AFAvo or AFAvo+dAvcis more than the effective aperture threshold value such as Av=5 (incase of F5.6) or not. In case the value of AFAvo or AFAvo+dAvc is lessthan the effective aperture threshold value, the AF mode and the FA modeis not performed because it is impossible to measure the defocusingquantity. then the program flow goes to the step #12. The reason why thedata of the maximum F number (the effective aperture value at thelongest focal distance) is set as the value of AFAvo is as follows. Thatis, it is impossible to adjust and detect the focal distance because theeffective aperture value is more than the effective aperture thresholdvalue on the way that the focal distance is changed from the shortestfocal distance to the longest focal distance. Therefore, it is inhibitedto perform the AF mode and FA mode in order to prevent the operation ofthe camera from being stopping suddenly during the operation of the AFmode and the FA mode.

At the step #8, it is determined whether the level at the terminal P₂₀is "High" or "Low", that is, whether the operation of the AFmicrocomputer MC₂ is set about or not. ln case the operation of the AFmicrocomputer MC₂ is set about, the program flow goes to the step #12.On the other hand, in case the operation has not been set about, Theterminal P₂₀ is made "Low" and the interrupt signal is inputted to theinterrupt terminal it₁ in the AF microcomputer MC₂, then the operationof the AF microcomputer MC₂ is set about. The operation of thesubroutine I is set about after a data request signal DTRQ is inputtedto the terminal P₂₆ from the AF microcomputer MC₂.

In the subrout1ne 1, the required data is transferred to the AFmicrocomputer MC₂ in series in accordance with the said data requestsignal. First of all, the terminal P₂₅ is made "High" at the step #60,and the conversion factor kL is set in a resistor IOR used for the SIOoperation at the step #61, then the operation of the SIO is performed.Next, AFAvo and the data (80H) which means the presence of the converterlens COV is set in the resistor IOR, and the SIO operation is performed.Then it is determined whether or not a flag CDEF which designateswhether the calculation of the exposure control value has been completedhas been set, in case the flag CDEF is set, then the exposure controlvalue has been already calculated, a desired effective aperture valueAvc and a desired exposure time Tvc are set in the register IOR and theSIO operation is performed. On the other hand , in case the flag CDEF isreset, then the calculation of the exposure control time has notcompleted yet, AFAvo and Tv™6 (1/60 sec) is set in the register IOR, andthe SIO operation is performed. After the SIO operation is completed,the terminal P₂₅ is made "Low" and the program flow is returned.

At the step #12, the ISO data is set in accordance with the condition ofthe Sv switch ISS, the UP switch UPS and the DOWN switch DOS. Next, atthe step #20 it is determined whether the release switch S₂ is closed ornot. In case the release switch S₂ is closed, the operation of thesubroutine II as shown in FIG. 3 is performed, on the other hand, incase the release switch S₂ is open, at the step #21 the analog output ofthe measured brightness LMAN inputted from a light measuring circuit LMCshown in FIG. 1 is converted into a digital form in reference to areference voltage VRAN inputted from the reference voltage power sourcearranged in the light measuring circuit LMC to a reference voltage inputterminal VRI. At the step #22, it is determined whether the data requestsignal is inputted from the AF microcomputer MC₂ or not. In case thedata request signal is inputted, the operation of the subroutine I isperformed and the program flow goes to the step #24. On the other hand,the data request signal is not inputted, the program flow goes to step#24 directly.

At the step #24, each mode is set in accordance with the condition ofthe mode switch MOSS, the UP switch UPS and the DOWN switch DOS, theprogram flow goes forward in accordance with the content of the moderegister MOR. At the step #28 in case the content of the mode registerMOR is "0" which corresponds to the P mode, the calculation of the Pmode is performed at the step #29 and the program flow goes to the step#38. Next, at the step #28, the content of the mode register MOR is "2"which corresponds to the A at the step #33 the effective aperture valueis set in accordance with the condition of the Av switch ASS, the UPswitch UPS and the DOWN switch DOS, the program flow goes to the step#35 through the step #34, then the calculation of the exposure time isperformed, and the program flow goes to the step #38. Moreover, in casethe content of the mode register MOR is "3" which corresponds to the Smode, at the step #31 the exposure time is set in accordance with thecondition the Tv switch TSS, the UP switch UPS and the DOWN switch DOS,the program flow goes to the step #37 through the step #32 , then thecalculation of the S mode is performed and the program flow goes to thestep #38. Finally, the content of the mode register MOR is "1" whichcorresponds to the M mode, the exposure time is set at the step #31 andthe effective aperture value is set at the step #33, then thecalculation of the M mode is performed at the step #36 and the programflow goes to the step #38.

At the steps #12, #31 and #33, the setting of the data Sv, Tvs and Avsare performed as follows. First of all, it is determined whether the Svswitch ISS, the Tv switch TSS, the Av switch ASS and the UP switch UPSor the DOWN switch DOS are closed or not. In case the UP switch UPS isclosed, 1/3 is added to the data Sv at the step #12, 1/2 is added to thedata Av at the step #31, 1 is added to the data Tv at the step #33. Incase the DOWN switch DOS is closed, 1/3 is subtracted from the data Svat the step #12, 1/2 is subtracted from the data Av at the step #31, 1is subtracted from the data Tv at the step #33. After that, it isdetermined whether each data is more than each predetermined thresholdvalue or not, only in case each data is more than the threshold value,the threshold value is set in each data. Moreover, the updating of eachdata is not performed after the setting of each data has been set oncewhen the UP switch UPS or the DOWN switch DOS has been closed. In casethe UP switch UPS or the DOWN switch DOS is closed again after theswitch is opened, the subsequent updating of the data is performed. Atthe step #24 when the mode is set, 1 is added to the content of theregister MOR after the mode switch MOSS and the UP switch UPS areclosed, then "0" is set in the content of the register MOR when thecarry is occurred, that is, the P mode→the M mode→the A mode→the S modeare set in turn. When the mode switch MOSS and the DOWN switch areclosed, 1 is subtracted from the content of the register MOR, "3" is setin the content of the register MOR when the borrow is occurred, that Pmode←the M mode←the A mode←the S mode are set in turn. Moreover, in caseof changing the mode, changing the mode can be performed only after theUP switch or the DOWN switch is opened once.

At the step #38, the flag CDEF is set since the calculation of theexposure control value is completed at the above steps, then it isdetermined whether the release switch is turned on or not. In case therelease switch is turned on, the program flow goes to the subroutine IIshown in FIG. 3, on the other hand, in case the release switch is turnedoff, the display data is outputted to the display unit DSP and theprogram flow goes to the step #42. In case of outputting the displaydata, the terminal P₂₇ is made "Low", the display data is set in theregister IOR, then the SIO operation is performed. At the step #42, itis determined whether the terminal P₃₇ is "Low" or not, in case theterminal P₃₇ is "Low", the program flow goes back to the step #2. On theother hand, in case the terminal P₃₇ is "High", when the UP switch UPSor the DOWN switch DOS is opened, therefore, the program flow goes tothe step # 43. Then it is determined whether the reset switch S₄ isturned on or not, in case the reset switch S₄ is turned on, (when theswitch S₄ is changed over to the terminal WE) it is determined whetherthe AF mode or FA mode is selected. Then in case the FA mode isselected, it become possible to the interrupt terminal it₀, the programflow goes back to the step #3. On the other hand, in case the AF mode isselected, the terminal P₂₁ is made "Low", an operation stop signal AFSTPof the AF microcomputer is outputted to the AF microcomputer MC₂ at thestep #45, then the AF microcomputer MC₂ outputs an AF stop signal AFENin accordance with the operation stop signal AFSTP. Upon inputting thesignal AFEN, the terminals P₂₀ and P₂₁ are made "High", then it isdetermined whether the reset switch S₄ is turned on or not at the step#48. In case the reset switch S4 is turned on, the program flow goesback to the step #3 through the step #49. That is, the above operationof reading, measuring the brightness of the object and calculation ofthe light measurement are performed in turn until the counterinterruption is enabled ever if the reset switch S4 is turned on withall the switches TSS, ASS, ISS, MOSS, UPS, DOS and S₁ turned off and theterminal P₃₇ is "High". Then in case the FA mode is selected, theoperation of the AF microcomputer MC₂ can be performed continuously. Onthe other hand, in case the AF mode is selected, the operation of the AFmicrocomputer MC₂ stops when the terminal P₃₇ becomes "High".

When it is determined that the terminal P₃₇ is "High", in case the resetswitch S₄ is turned off, the operation of the AF microcomputer MC₂ stopseven though the AF mode or the FA mode is selected. Then the counterinterruption is inhibited at the step #51, it is permitted to interruptto the terminal it₀ at the step #52. Next, a permission signal STPOK ofstopping the operation of the AF microcomputer MC₂ is inputted at thestep #53, the flag CDEF is reset at the step #54, it is inhibited tooutput the reference clock pulses STCL at the step #55, the transistorBT₀ is turned off at the step #56, then the microcomputer MC₁ stops.

In the following, the counter interruption will described. As soon as apredetermined time (for example, five seconds) has passed after it isdetermined that the terminal P₃₇ is "High" and the reset switch S₄ isturned on, the counter interruption is performed from the step #120.First of all, it is determined whether the FA mode or the AF mode hasbeen selected. In case the FA mode is selected, when the operation ofthe AF microcomputer MC.sub.₂ has been performed continuously, the AFmicrocomputer MC₂ is stopped, and the program flow goes to the step#124. On the other hand, in case the AF mode is selected, when theoperation of the AF microcomputer MC₂ has been already stopped, theprogram flow goes to the step #124. Moreover, the counter interruptionis inhibited and it is permitted to interrupt to the interrupt terminalit₀. After the permission signal STPOK of stopping the operation of theAF microcomputer MC₂ is inputted at the step #126, the reference clockpulses STCL are stopped at the step #127 and the transistor BT₀ isturned off. Then the flag CDEF is reset at the step #129 and theoperation is made to stop.

ln the following, the operation of the subroutine II will be described.At the step #80, it is determined whether the flag CDEF has been set ornot, in case the flag CDEF has been reset, when the calculation of theexposure control value has not been completed, the program flow goesback to the main routine. In case the flag CDEF has been set and thecalculation of the exposure control value has been completed, theprogram flow goes to the step #81. Then a signal INREL which designatesthat the operation of controlling the exposure has been performed isoutputted. After the signal AFEN is inputted at the step #82, theprogram flow goes to the operation of the exposure control. Table 4shows the correlation between the outputs of the terminals P₄₁, P₄₂ andP₄₃, the output of a driver DEDR, the magnet in operation and theoperation of the camera.

                  TABLE 4                                                         ______________________________________                                                                               Mag-                                   P.sub.41                                                                           P.sub.42                                                                             P.sub.43                                                                             X.sub.1                                                                           X.sub.2                                                                           X.sub.3                                                                           X.sub.4                                                                           X.sub.5                                                                           net   Operation                        ______________________________________                                        L    H      H      H   L   L   L   L   RELC  release                          H    L      H      L   H   L   L   L   APSC  interrupt                                                                     stopping                                                                      down operation                   L    L      H      L   L   H   L   L   MRC   mirror up                        H    H      L      L   L   L   H   L   1CC   first curtain                                                                 start                            L    H      L      L   L   L   L   H   2CC   second curtain                                                                start                            H    H      H      L   L   L   L   L   x     operation                                                                     disable                          ______________________________________                                    

In the operation of controlling the exposure, of all, the operation ofthe stopping down of the aperture is set about after the operation ofreleasing, the time T₀ is counted. The pulses of a pulse generatingdevice APC are inputted to an event counter APCO through a terminalCLI₁, the step data AVc-Avo for stopping down of the aperture, which arepreset in the counter, are subtracted by one each time said pulse fromthe pulse generating device APC is inputted. When the content of thecounter APCO become "0", the interruption is enable to stop the stoppingdown of the aperture at the step #88, then the program flow goes back tothe subroutine II. On the other hand, in the subroutine II, the mirroris raised after the operation of counting the time T₀ is completed, thenthe time T₁ is counted. The operaion of stopping down of the aperture isstopped during the time period T₀ +T₁. After the time T₁ has passed, themirror is completely raised, the first curtain begins to run at the step#91. After the time 2^(-Tvc) has passed, the second curtain begins torun at the step #94. When the reset switch S₄ is turned off, the signalINREL representing the period of controlling the exposure is eliminatedwith the flag CDEF reset and the program flow goes back to the step #42in the main routine.

In FIG. 1, MLMC denotes a CCD comprising at least two pairs of the lightreceiving unit which receive the light passed through the photographiclens and distributed by a known optical distribution system. Theinterface circuit INF outputs "High" pulse to the terminal φR for makingthe charge storing unit in the CCD at a predetermined voltage. When thesaid pulse becomes "Low", storing the charge in accordance with thereceived light quantity in the light receiving component of the chargestoring unit is set about. In the interface circuit INF, a monitoroutput AMO outputted from the light receiving quantity monitor unit ofthe CCD is compared with the reference level, the transfer pulse isoutputted to the terminal φT as soon as the monitor level reaches thereference level. In the CCD, the charge stored in the charge storingunit is transferred to the transfer gate (an analog shift register), asignal ANO of the stored charge which corresponds to the received lightquantity in each light receiving unit is outputted in turn in accordancewith the pulse used for transferring from the terminals φ₁, φ₂ in theinterface circuit INF. When storing the charge is completed and theinterface circuit INF outputs the transfer pulse to the terminal φT, theinterface circuit INF outputs a signal INEN which designates that theoperation of storing the charge is completed to the AF microcomputerMC₂.

The interface circuit INF converts an analog signal ANO inputted to adigital signal, and outputs a "Low" pulse signal ADEN, which designatesa timing used for inputting the converted data to the AF microcomputerMC₂, whenever the said A-D conversion is completed. Then the interfacecircuit INF outputs the A-D converted data to the input port D₀ in theAF microcomputer MC₂ through a bus ADD. When the storing time has passedbeyond a predetermined time and the monitor output AMO is less than thereference level, the AF microcomputer MC₂ outputs a "Low" pulse INSTPfor stopping the operation of storing the charge in the CCD compulsorilyand make the operation of storing the charge compulsorily. After that,in accordance with the above stop of the operation of storing thecharge, the interface circuit INF amplifies the input signal AN inaccordance with the monitor level AMO at that time when the operation ofstoring the charge is made to stop, and A-D convert the said amplifiedsignal to a digital signal. Then the interface circuit INF transfers theA-D converted signal to the AF microcomputer MC₂.

MCC denotes a control circuit for the motor MO. First of all, therotation of the motor MO is transferred to a driving member in theconverter lens COV through a transferring member not shown.

Said rotation of the motor MO is transferred to a driven member in theinterchangeable objective lens LE through a transferring member in theconverter lens COV and focusing is performed in the optical system ofthe interchangeable objective lens LE. Moreover, the rotation of themotor is transferred to an encoder ENCC, which produces pulsesrepresenting therrotation of the motor MO (referred to as rotationpulse) in accordance with the rotation of the motor. The rotation pulsesare inputted to an event counter in the AF microcomputer MC₂ through theterminal CLI₀. Said event counter is set by the data of a predeterminedand required rotation number of the motor MO. The data in the eventcounter is subtracted in accordance with the pulse. When the opticalsystem for focusing in the interchangeable objective lens is moved bysaid predetermined length, the content of the event counter becomes "0",the interruption from the event counter is performed and the rotation ofthe motor MO is made to stop or to be changed from high speed to the lowspeed. The motor control circuit MCC makes the motor MO rotate in aclockwise direction when the terminal P₄ in the AF microcomputer MC₂ is"Low" and makes the motor MO rotate in a counterclockwise direction whenthe terminal P₅ in the AF microcomputer MC₂ is "Low". On the other hand,the motor control circuit MCC stops the motor MO when the both terminalsP₄ and P₅ is "High" . Moreover, the motor MO is controlled to rotate atthe high speed when the terminal P₆ in the AF microcomputer MC₂ is"High", on the other hand, the motor MO is controlled to rotate at thelow speed when the terminal P₆ is "Low".

A light emitting diode RFL is used for displaying the condition that theimage of the object is out of focus backward, a light emitting diode IFLis used for displaying the condition that the image of the object is infocus, and a light emitting diode FFL is used for displaying thecondition that the image of the object is out of focus forward. Theabove three light emitting diodes are selectively turned on by the "Low"state of the terminals P₇, P₈ and P₉.

FLS denotes a switch used for locking the lens in the focused condition,when the switch FLS is closed, the motor MO is made to stop and theoptical system for photographing is fixed at the position that the imageof the object is in focus. When a switch AMS is changed over to theterminal AF, the AF mode is selected. On the other hand, when the switchAMS is changed over to the terminal FA, the FA mode for only displayingthe in focus condition is selected. A switch SNS is switched to theterminal SIN during the single mode in which the AF microcomputer MC₂ isoperated by itself such as the following mode. That is, for example, thesingle mode is the operation mode of the AF microcomputer MC₂ when theinterchangeable objective lens with the circuit used for controlling thefocal distance automatically is set as an AF lens, when the circuit usedfor controlling the focal distance automatically is set in a camera witha fixed lens for taking picture which can not be changed, or when theoperation of the AF microcomputer MC₂ is checked. On the other hand,when the circuit arrangement used for automatic focus controlling ismounted in the body of the camera with the interchangeable objectivelens, the switch SNS is switched to the AF microcomputer MC₂ through aterminal NOM, then the AF microcomputer MC₂ operates in the normal mode.Moreover, the both operating program of the single mode and the normalmode are stored in the AF microcomputer MC₂, one of the two program isused in accordance with the condition of the switch SNS. The switch SNSis set on or off in the production process of the camera system. Theswitch SNS is so arranged in the camera that only particular operatorscan access it.

FIG. 5 shows an example of a circuit arrangement in which an AF controlcircuit such as the AF microcomputer MC₂ is mounted in theinterchangeable lens. In this case, the switch is connected to theterminal SIN. Moreover, the data of the predetermined conversion factorof the lens is inputted to the terminals P₇, P₉ -P₁₁ and P₁₃ -P₁₆. Thatis, the data outputted from a zoom code plate FCP in accordance with theset focal distance is converted to the data of the conversion factorthrough a decoder DCC, the data of the conversion factor is inputted tothe above terminals P₇, P₉ -P₁₁ and P₁₃ -P₁₆. Moreover, as the displaydevice used for displaying the in focus condition, a buzzer BZcontrolled by a control circuit SOC is employed without any emittingdiode therefore. The operation of the AF microcomputer MC₂ is set aboutas soon as the driving power is supplied. Therefore, it is not necessaryto provide a function of the said interrupt terminal it₁, the AFmicrocomputer MC₂ is connected to the driving power line through thepull up resistor. As the AF operation is stopped when the driving poweris cut off, or when the exposure control operation of the camera is setabout, it is not necessary to provide the said interrupt terminal it₂and the AF microcomputer MC₂ is connected to the driving power directly.In the above description, it is not necessary to read the serial dataafter the data of the lens LE is transferred to the AF microcomputer MC₂through the microcomputer MC₁, therefore, a serial input terminal SIIN₀and the clock input terminal SICK₀ are connected to the driving powerline directly.

Referring to the flow charts shown in FIGS. 6 and 11, the operation ofthe AF microcomputer MC₂ will be described. The operation of the AFmicrocomputer MC₂ is set about from the step No. 1 as soon as the powerswitch is turned on. At the step No. 1, all the flags are reset. In caseeach flag is set "0" at the initial condition, it is easy to initializeall the flags. At the step No. 2, all the output data (the dark outputof the CCD) on the condition that the light is projected to the CCD areset "0". Next, at the step No. 3, the signal outputted from the switchSNS used for switching the single mode or normal mode is read. In casethe said signal is "High", this case corresponds to the lens single bodymode (the single mode), the program flow goes to the step No. 9. Thenthe input and output ports used in the single mode are initialized atthe steps No. 9 and No. 10. However, in this case it is enough that theports used only as the output mode are initialized at the steps No. 9and No. 10, because all the input and output ports are set as the inputmode at the power on reset performed when the above power switch isturned on. Then at the step No. 11 and No. 12, it is permitted tointerrupt to only the terminal it₃, the program flow goes to the stepNo. 36 which is the head step of the storing routine. In case of thesingle mode, the operation of the said single mode is set about byturning the power switch on. In case of the focusing mode only one shotAF control mode (the position of the lens is fixed after the AF controlis once perfected) is performed. On the other hand, at the step No. 3,in case it is determined that the terminal P₁₂ to which the signaloutputted from the switch SNS is inputted is "Low". This casecorresponds to the camera mode (normal mode), at the steps No. 4, No. 5and No. 6, the input and output ports are initialized. Then at the stepsNo. 7 and No. 8, it is permitted to interrupt to the terminals it₁, it₂and it₃ and the program flow goes to the operation of the stop mode. Thestop mode is one of functions provided in the microcomputer, which is apower saving mode with the clock pulses stopped holding the content ofthe memory unchanged. Using the power saving mode prevents fromconsuming the unnecessary power. In the operation of the AFmicrocomputer MC₂, the program flow goes out from the stop mode byperforming the reset or inputting any interrupt signal. Moreover, thefollowing is not shown in the flow charts, the microcomputer MC₁ canperform the power on reset operation like the AF microcomputer MC₂. Whenthe power on reset operation is made to stop, the microcomputer MC₁outputs the signal AFSTP in order to stop the AF operation. As soon asthe AF microcomputer MC₂ receives the signal AFSTP, it is determinedwhether it is permitted or not that the operation of the AFmicrocomputer MC₂ is made to stop. In case it is permitted, the AFmicrocomputer outputs the "Low" signal STPOK which represents that it ispermitted that the operation of the AF microcomputer MC₂ is made tostop. Then the microcomputer MC₁ stops to output the reference clockpulses STCL and the operation of the both microcomputers MC₁ and MC₂ ismade to stop.

In case of the normal mode, when the AF microcomputer MC₂ sets about,the AF microcomputer outputs a "Low" signal AFSTA. Then the interruptsignal inputs to the interrupt terminal it₁, the program flow goes tothe step No. 14. At the step No. 14, the terminal P₁₃ is made "High" andit is informed to the microcomputer MC₁ that the reference clock pulsesmust be continued, and in turn at the step No. 15, the terminal P₁₄ ismade "Low", it is informed to the microcomputer MC₁ that the operationof the AF microcomputer MC₂ sets about. At the step No. 16 through No.20, it is permitted to interrupt to the interrupt terminal it₂ and it₃only in case of a necessary interruption, on the other hand, anunnecessary interruption is inhibited. At the step No. 21, the conditionof the after a release flag AFRF which designates whether the releaseoperation has been operated is detected, then it is determined whetheror not the interruption to the interrupt terminal it₁ was performedafter the release operation. In case the flag AFRF is "1", the programflow goes to the step No. 22 with the interruption performed after therelease operation. The operation from the step No. 21 will be describedlater. In case the flag AFRF is "0" at the step No. 21, the program flowgoes to the step No. 27. The operation from the step No. 27 is anoperation of a first serial communication that the data are transferredin series between the microcomputer MC₁ and the AF microcomputer At thestep No. 27, "0" is set in the serial data counter k, wherein the datahas four data and the length of each data is eight bits. Next, theinterruption in the serial communication is permitted. When theinterruption in the serial communication is performed, eight pulses ofthe serial clock pulses SICK are inputted to the terminal SICK₀. Afterthe eight pulses of the serial clock pulses SICK are inputted to theserial data register, the interruption is performed. At the step No. 30,the terminal P₁₆ is made "Low" and the demand signal DTRQ in the serialcommunication is outputted to the microcomputer MC₁. After themicrocomputer MC₁ receives the said demand signal DTRQ, the data, thenthe microcomputer MC₁ makes the terminal P₂₅ "High". Making the terminalP₂₅ "High" is performed in order to prevent the data passing through theserial communication line from interfering. The said "High" signal isused for selecting each circuit because the serial communication line isused for communicating with the display unit DSP, the ROM in the lens LEand so on. When the microcomputer MC₁ communicates with the AFmicrocomputer MC₂ in series, the microcomputer MC₁ makes the terminalP₂₅ "High", then the serial communication line can be used tocommunicate with the AF microcomputer When the.said selecting signalCSAF is "Low", the AF microcomputer MC₂ closes the gate of the serialclock pulses SICK. On the other hand, when the selecting signal CSAF is"High", the AF microcomputer MC₂ opens the gate for the serial clockpulses SICK. Therefore, the selecting signal CSAF prevents the AFmicrocomputer MC₂ from sending and receiving from and to the othercircuit.

After the microcomputer MC₁ outputs the signal DTRQ in order to performthe serial communication, the microcomputer MC₁ waits until all the dataare inputted by the interruption at the step No. 31. After the eightpulses the serial clock pulses SICK are inputted, the interruption isperformed. Then the program flow goes to the step No. 225 shown in FIG.6. The data inputted to the serial register are transferred to aregister SDR_(k) at the step No. 225, and the next register SDR_(k+1) isset at the step No. 226. At the step No. 227, the microcomputer MC₁outputs a "High" signal to the terminal DTRQ and the program flow goesto the step No. 31 in FIG. 7. After the interruption has been performedfour times, with all the data inputted, the content of the serial datacounter is "4". Then the program flow goes to the step No. 32 throughNo. 31, then the serial interruption is inhibited and the serialcommunication is completed. At the step No. 33, it is determined whetherthe signal inputted from the switch AMS used for selecting the AF modeor the FA mode to the terminal P₁₁ is "High" or not. In case the signalis "High", when the AF mode has been selected, a focus mode flag FMF ismade "0". On the other hand, in case the signal is "Low", when the FAmode has been selected, "1" is set in the flag FMF. Then the programflow goes to the integral routine from the step No. 36. In case of thesingle mode, the program flow goes from the step No. 12 to the step No.36 because it is not necessary to perform the serial communication.

At the step No. 36, a low light flag LLF is reset. The flag LLF is setwhen the charging time of the cc has passed for a predetermined maximumtime in case of an object with the low brightness. At the step No. 37,the content of the event counter is set in a register n₁. The eventcounter is a subtraction counter which subtracts "1" each time duringwhich the negative edge of the pulses are inputted to the terminal CLI₀.The pulses inputted from the encoder circuit ENCC detecting the rotationquantity of the motor MO are inputted to the said terminal CLI_(O). Thecontent of the event counter (the content of the register n₁) is usedfor the correction of the amount of the movement of the lens when thedefocus quantity is being measured during driving the motor MO, thecontent of the event counter is not used when the motor MO is notrotating. At the step No. 38, a timer is reset, and the interruption ofthe timer is permitted at the step No. 39. At the step No. 40, the "Low"signal is outputted to the line terminal P₁ for a predetermined time andthereby the interface circuit INF is made to set about the integraloperation of the CCD. At the step No. 41, the timer starts and count theintegral time. At the step No. 42, it is determined whether the integralcompletion signal is inputted from the interface circuit INF or not. Thesignal INEN becomes "Low" when the charging quantity of the CCD reachesa predetermined proper value, the "Low" signal INEN represents thecompletion of the interruption of charge in the CCD. After the signalINEN is detected "Low", when charging is completed, the program flowgoes to the step No. 49 through No. 48. In case the signal INEN is"High", it is detected whether the counting time of the timer reaches atime t₁ or not. The time t₁ corresponds to the time interval at which itis detected that the lens is moved to the end position. In case anypulse from the encoder circuit is not inputted, it is determined thatthe lens has been moved to the end position. In order to perform thedetermination, at the step No. 45, the subroutine shown in FIG. 11 whereit is detected that the lens has been moved to the end position isexecuted. At the step No. 43, in case the timer value is not equal tothe time t₁, the program flow goes to the step No. 44, then it isdetermined whether the timer value reaches the maximum integral time t₂or not. In case the timer value reaches the time t₂, the program flowgoes to the step No. 46. In case the timer value does not reach the timet₂ , the program flow goes back to the step No. 42, then the aboveoperation is repeated. When the integral operation of the CCD iscompleted until the timer value becomes a time t₀ (t₀ >t₂), the objecthas high brightness, then a flag HLF is set. On the other hand, in casethe brightness of the object is low, the flag HLF is reset and theprogram flow goes to the step No. 49.

When the charging time reaches the maximum charging time, a "Low" signalis outputted to the terminal P₂ at a predetermined time and the integraloperation is stopped compulsorily. At the step No. 47, the low lightflag LLF is set and the high light flag HLF is reset, the program flowgoes to the step No. 49. The timer interruption is inhibited at the stepNo. 49, the timer is made to stop at the step No. 50. At the step No.51, the content of the event counter is set in a register n₂ in the sameway as made in the step No. 37. A digital value converted from theoutput of the CCD in the interface circuit is inputted as a signal ADDevery predetermined interval since the integral operation is completed.At the step No. 52, the said signal ADD is inputted to the input port D₀at the negative edge of the timing signal ADEN inputted to the terminalP₃ and the signal ADD is stored in a memory.

After input of the data is completed, the terminal P₁₂ is checked, andin case the terminal P₁₂ is "Low", under the normal mode, the programflow goes to the step No. 54. On the other hand, in case the terminalP₁₂ is "High", under the single mode, the program flow goes to the stepNo. 55. At the step No. 54, the value subtracted the data of the darkoutput from the respective output data of the CCD is set as the data forcompensation of the dark output.

At the step No. 55, the subroutine of the focus lock check shown in FIG.6 is called. The subroutine of the focus lock check sets about from thestep No. 229. At the step No. 229, the flag FMF is checked. In case theflag FMF is "1", under the FA mode, the program flow returns withoutchecking the focus lock switch FLS. On the other hand, in case the flagFMF is not "1", under the AF mode, the program flow goes to the step No.230, then the signal inputted from the focus lock switch FLS is checked.In case the signal inputted from the focus lock switch FLS is "High",when this case does not mean the condition of the focus lock, theprogram flow goes to the step No. 236. On the other hand, in case thesignal inputted from the focus lock switch FLS is "Low", when this casemeans the condition of the focus lock, the program flow goes to the stepNo. 231. At the step No. 231, a focus lock flag FLF is checked, in casethe flag FLF is "1", the program flow returns. In case the flag FLF is"0", the program flow goes to the step No. 232, then the stop signal isoutputted to the motor MO. Next, a motor flag MOF is reset. Then thecounter interruption is inhibited, and the flag FLF of the focus lock isset. After that, the program flow returns to the step No. 36. Moreover,at the step No. 230, in case the signal inputted from the focus lockswitch FLS is "High", the focus lock flag FLF is checked at the step No.236. In case the flag FLF is "0", the program flow returns determiningthat the previous routine already executed is not the focus lock. On theother hand, in case the flag FLF is "1", the focus lock flag FLF isreset at the step No. 237 due to the condition that the focus lock isalready released. Next, it is determined whether a low contrast flagLCF₀ is "1" or not. When the low contrast flag is "1", this case meansthe condition that the contrast of the image is low. In case the flagLCF₀ is "1", all the low contrast flags LCF₀, LCF₁, LCF₂ and LCF₃ arereset and initialized, and the display is turned off at the step No.240, then the program flow returns to the step No. 36. On the otherhand, in case the flag LCF₀ is not "1" at the step No. 238, the programflow goes to the step No. 240 without performing the step No. 239, thenthe display is turned off at the step No. 240 and the program flowreturns to the step No. 36.

The program flow goes back to the step No. 57 of the main routine, thepreparation of the serial communication will be performed again. Theoperation of the steps No. 57 through No. 59 is the same operation asthe operation of the steps No. 27 through No. 30. The serialcommunication is performed in order to input various data. The operationof the serial communication is performed by interrupting during thecalculation at the step No. 60. On the other hand, in case the terminalP₁₂ is "High", under the single mode, the program flow goes to the stepNo. 55. Then the conversion data are inputted from the decoder circuitDCC shown in FIG. 5 to the terminals P₇, P₉ -P₁₁ and P₁₃ -P₁₆, and thedata is stored in a memory. The program flow goes to the step No. 60. Atthe step No. 60, the predetermined calculation is performed inaccordance with the data inputted from the CCD, wherein a defocusingquantity Δε and a defocusing direction are calculated. At the step No.61, the serial interruption is inhibited. the program flow goes to thestep No. 62 wherein the contrast determination is performed. In thecontrast determination, it is determined whether the brightness of theimage can be detected in accordance with the output of the CCD or not.

At the step No. 62, in case it is determined that the image has a lowcontrast, the program flow goes to the step No. 63. On the other hand,in case it is determined that the image has the normal contrast, theprogram flow goes to the step No. 93. Next, at the step No. 63, it isdetermined whether the flag FLF representing the condition of the focuslock is "1" or not. In case the flag FLF is "1", the program flow goesto the step No. 82. At the steps No. 82 through No. 85, displaying thecondition of the low contrast (turning the light emitting diodes RFL andLFL on and off continuously) and setting of the low contrast flag LCF₀is performed. Then the program flow goes to the step No. 36 in order tomeasure again. On the other hand, in case the flag FLF is not "1", whenthis case does not mean the condition of the focus lock, the programflow goes to the step No. 64. In case the flag FMF is "1 ", when the FAmode has been selected, the program flow goes to the step No. 82. On theother hand, In case the flag FMF is not "1", when the AF mode has beenselected, the program flow goes to the step No. 65, then it isdetermined whether the motor MO is rotating or not.

In case the motor MO stops, the program flow goes to the step No. 66,then it is determined by the low contrast flag LCF₃ (the flag isreferred to as a scan inhibit flag of the low contrast) whether scanningwith the low contrast can be performed or not. In case the flag LCF₃ is"1", when scanning is inhibited, the program flow goes to the step No.82. On the other hand, in case the flag LCF₃ is not "1", when scanningwith the low contrast is permitted, the program flow goes to the stepNo. 67. In the steps No. 67 through No. 69, displaying the condition ofthe low contrast and setting the low contrast flag LCF₀ are performed.Next, at the step No. 70, the low contrast flag LCF₁ (the scan flag ofthe low contrast) is set. At the step 71, it is determined by the lowlight flag LLF whether the object has low brightness or not. In case theflag LLF is "1", when the object has low brightness, the low contrastflag LCF₂ which is the inverse of the scan flag is set at the step No.73, then the program flow goes to the step No. 76. In case of the objectwith low brightness, the above operation is performed in order toperform scanning with the low contrast only in such a direction as thelens moves to the body of the camera and in order that the lens may moveinto the ∞ position when the lens cap is mounted. In case the flag LLFis not "1", when the object has not low brightness, the program flowgoes to the step No. 72, then the low contrast flag LCF₂ is reset. Atthe step No. 74. in case of the rear defocusing, that is, when the imageis out of focus backward, a driving direction flag DDF is reset at thestep No. 75. On the other hand, at the step No. 74, in case of the frontdefocusing, that is, when the image is out of focus forward, the drivingflag DDF is set at the step No. 76, then the program flow goes to thestep No. 77. At the step No. 77, "High" is outputted to the terminalP₁₆, the rotation speed of the the motor MO is set in a high speed mode.The motor flag MOF is set at the step No. 78, then at the step No. 79,the driving power is supplied to the motor MO with the polaritycorresponding to the driving direction flag DDF. Then scanning isperformed and the program flow goes back to the step No. 36.

At the step No. 65, in case it is determined that the motor MO isrotating, it is determined whether the flag LCF₁ is "1" or not at thestep No. 86. That is, it is determined whether the motor MO is rotatingby scanning with the low contrast or by driving on the normal condition.In case the flag LCF is "1", when the motor MO is rotating by scanningwith the low contrast, detecting whether the lens is at the end positionor not is performed. Then the program flow goes back to the step No. 36and scanning with the low contrast is set about continually. On theother hand, at the step No. 86, in case the flag LCF₁ is not "1", whenthe motor MO is rotating by driving on the normal condition, the programflow goes to the step No. 87. First of all, the motor is made to stopand the motor flag MOF is reset. Then the low contrast flag LCF₀ is set,the condition of the low contrast is displayed and the program flow goesback to the step No. 36 in order to measure again.

At the step No. 62, it is determined that the object has not lowcontrast, the program flow goes to the step No. 93. At the step No. 93,it is determined whether the flag FMF is "1" or not. In case the flag is"1", when the FA mode has been selected, the program flow goes to thestep No. 97. At the step No. 97, the low contrast flag LCF₀ is checked.In case the low contrast flag LCF₀ is "1", when the object has lowcontrast, the low contrast flag LCF₀ is reset at the step No. 98, thedisplay of the condition of the low contrast is turned off, then theprogram flow goes to the step No. 106. On the other hand, in case theflag FMF is not "1", under the AF mode, the program flow goes to thestep No. 94. At the step No. 94, the scan inhibit flag LCF₃ of the lowcontrast is set. Therefore, scanning under the low contrast is inhibitedso far as the object has the normal contrast once. At the step No. 95,it is determined by the low contrast flag LCF₀ whether the object hashad the low contrast up to now or not. In case the flag LCF₀ is "1",when the object has had the low contrast, the program flow goes to thestep No. 101. At the step No. 101, the driving power stops to besupplied to the motor MO. Next, the motor flag MOF is reset at the stepNo. 102, the low contrast flags LCF₀, LCF₁ and LCF₂ are reset. Then itis determined whether the terminal P₁₂ is "High" or not at the step No.104. In case the terminal P₁₂ is not "High", when the normal mode hasbeen selected, the display of the condition of the low contrast isturned off and the program flow goes back to the step No. 36 in order tomeasure. again. On the other hand, at the step No. 104, in case theterminal P₁₂ is "High", the program flow goes back to the step No. 36directly.

At the step No. 95, in case the flag LCF₀ is not "1", when the objecthas not had the low contrast, the program flow goes to the step No. 96.Then the focus lock flag FLF is checked, in case the flag FLF is not"1", when this case is not the condition of the focus lock, the programflow goes to the step No. 121. On the other hand, in case the flag FLFis "1", when this case is the condition of the focus lock, the programflow goes to the routine of the FA mode performed from the step No. 106.At the step No. 106, a focus width ZFA in the FA mode is set. The focuswidth ZFA in the FA mode varies in accordance with the maximum F numberAFAv₀ used for controlling the focal distance automatically. In thepresent embodiment, ZFA is set as (AFAv₀ +α)×β, wherein c is a biasvalue, β is an appropriate factor and ZFA has the unit μm. Next, theprogram flow goes to the step No. 108, it is determined whether thedefocusing quantity Δε is within the range of the focus width ZFA ornot. In case the defocusing quantity Δε is within the range of the focuswidth ZFA, the program flow goes to the step No. 119. On the other hand,in case the defocusing quantity Δε is not within the range of the focuswidth ZFA, the program flow goes to the step No. 111.

In the following, the operation on the condition that the defocusingquantity Δε is within the range of the focus width ZFA will bedescribed. First of all, at the step No. 119, the AF microcomputer MC₂outputs a "High" signal to the terminal P₁₄ in order to inform it to themicrocomputer MC₁ that the image of the object has been in focus. Next,at the step No. 120, the light emitting diode IFL representing that theimage of the object is in focus is turned on, and the program flow goesback to the step No. 36 in order to measure the light again. In theroutine from the step No. 111, the operation on the condition that thedefocusing quantity Δε is not within the range of the focus width ZFA isperformed. At the step No. 111, the AF microcomputer MC₂ outputs a "Low"signal to the terminal P₁₄ in order to inform it to the microcomputerMC₁ that the image of the object is out of focus. Then the AFmicrocomputer MC₂ outputs a "High" signal to the terminal P₈ and thedisplay of the in focus condition is turned off. At the step No. 113, itis determined whether the flag FMF is "1" or not. In case the flag FMFis not "1", when the AF mode has been selected, the program flow goes tothe step No. 115. In case of the AF mode, the program flow comes to thisroutine only on the condition of the focus lock. Then the display of thedefocus is turned off and the program flow goes back to the step No. 36in order to measure again. In case of the FA mode, when the program flowcomes to the step No. 114, the defocusing direction is determined. Incase the image of the object is out of focus backward, the lightemitting diode RFL is turned on at the step No. 116. On the other hand,in case the image of the object is out of focus forward, the lightemitting diode FFL is turned on at the step No. 117, then the programflow goes back to the step No. 36 in order to measure again.

After the program flow comes from the step No. 96 to the step No. 121shown in FIG. 9, it is determined whether the converter lens COV ismounted or not. The mounting information of the converter lens COV istransferred from the microcomputer MC₁ by the serial communication atthe step 31 shown in FIG. 7. In case the converter lens COV has not beenmounted, it is determined whether the conversion factor kL is less thanthe threshold level K₁ or not at the step No. 122. The threshold levelK₁ is the conversion factor at the threshold level that it becomesdifficult for the motor MO to stop within the range of a minimum value bof the focus width when the preciseness of stopping the motor MO istaken account into. At the step No. 122, in case it is determined thatthe conversion factor kL is more than or equal to the threshold levelK₁, the minimum value b is set as the focus width ZFA in the AF mode atthe step No. 124, then the program flow goes to the step No. 126. At thestep No. 122, in case the conversion factor kL is less than thethreshold level K₁, Av×a, that is, the value multiplied the effectiveaperture value Av during taking a picture by a value "a" is set as thefocus width ZFA, wherein the value "a" is predetermined so that thevalue of ZFA is more than the minimum value b, that is, the image of theobject may be in focus within the range of the position at which thelens moves freely. Therefore, widening the focus width is to make themotor MO rotate smoothly at the range at which it is difficult tocontrol the rotation of the motor MO. At the step No. 121, in case it isdetermined that the converter lens COV is mounted, the program flow goesto the step No. 125. (Av+C)×a, that is, the value multiplied the value,which is made by which the effective aperture value Av is added to abias value C, by a factor "a", is set as the focus width ZFA. Adding thebias value C prevents it from being more difficult to control the motorMO when the converter lens COV is mounted than the case "ZAF Av+a" ofthe step No. 123.

After setting of the focal width is completed, the defocusing quantityand the focus width are respectively converted to pulse count values forthe encoder ENCC at the step No. 126. That is, the converted value Δ_(n)', which is the pulse count value of the defocusing quantity, is made bymultiplying the defocusing quantity Δε by the value multiplied theconversion factor kL in the lens by the conversion factor kB in the bodyof the camera. Similarly, a converted value ZAFC, which is the pulsecount value of the focus width ZFA, is made by multiplying the focuswidth ZFA by the value multiplied by the conversion factor kL in thelens by the conversion factor kB in the body of the camera. Moreover, itis necessary for the data kL to convert to the conversion factor in adecimal system, because the conversion factor transferred from themicrocomputer MC₁ is the data kL which consists of the fractional partand the exponential part.

At the step No. 127, it is determined by the motor flag MOF whether themotor MO is rotating or not. In case the motor flag MOF is not "1", whenthe motor MO stops, a count value Δn' of the defocus pulses is set as anumber of driving pulses at the step No. 128, then the program flow goesto the step No. 135. On the other hand, at the step No. 127, the motorflag MOF is "1", when the motor MO is rotating, it is determined whetherthe lens is at the end position. In case the lens is not at the endposition, the count value of the encoder is read into the register n₃ assoon as the operation at the step NO. 131 is completed. The compensationquantity Δn"=n₁ -n₃₋(n₁ -n₂)/2 by moving is calculated at the step No.133, and the compensation defocus count value Δn=Δn'-Δn" is calculatedin order to compensate the moved quantity of the lens at the step No.134. Then, at the step No. 135, it is determined whether the defocuscount value Δn is within the range of the count value of a focus widthZFAC or not. In case Δn is more than ZAFC, the program flow goes to thestep No. 149. In case Δn is less than or equal to ZAFC, when the imageof the object is in focus, the program flow goes to the step No. 136. Atthe step No. 136, the driving power stops to be supplied to the motorMO, then the motor flag MOF is reset at the step No. 137. Next, at thestep No. 138, the compensation defocus count value Δ n is set as theformer defocus quantity ΔnL. Then the program flow goes to the step No.139, it is determined whether the terminal P₁₂ is "High" or not. In casethe terminal P₁₂ is "High", when the single mode has been selected, theprogram flow goes to the step No. 145. The AF microcomputer MC₂ outputs"Low" to the terminal P₈ at the step No. 145, the buzzer informing thein focus condition vibrates at a predetermined time at the steps No. 146and No. 147. In case of the single mode, one measuring operation iscompleted. Then the AF microcomputer MC₂ waits the interrupt signal atthe step No. 148.

At the step No. 139, in case the terminal P₁₂ is "Low", under the singlemode, then an in focus flag AFIFF is set at the step No. 140 and a firstout flag FOF is reset. Then the AF microcomputer MC₂ outputs "High" tothe terminal P₁₄ in order to inform it to the microcomputer MC₁ that theimage of the object has been in focus. Then the AF microcomputer MC₂outputs "High" to the terminals P₇ and P₉ and output "Low" to theterminal P₈ in order to turn the light emitting diode IFL on. Theprogram flow goes back to the step No. 36 in order to measure again.

Moreover, at the step No. 135, in case it is determined that Δ is morethan ZAFC, the AF microcomputer MC₂ outputs "Low" to the terminal P₁₄ inorder to inform it to the microcomputer MC₁ that the image of the objectis still out of focus. Next, at the step No. 150, in case it isdetermined that the motor flag MOF is "1", the program flow goes to thestep No. 155, then n₃ is set as the former defocus count value ΔnL. Onthe other hand, in case the motor flag MOF is not "1", when the motor MOstops, the program flow goes to the step No. 151. In the following,setting of the near zone near the focus width will be described. Firstof all, there is provided two kinds of width of the near zone, that is,one is width Nzn used for determining whether the lens has been in thenear zone when the lens is moved from the outside of the near zone intothe inside of the near zone, and another one is width Nzw (Nzw>Nzn) usedfor determining where the lens is in order to catch up with the objectat a low speed. Nzw is set as the comparison value with the results ofthe pulse count value ZAFC multiplier by "j" (j>1), on the other hand,Nzn varies in accordance with the rotating quantity calculated. First ofall, there is provided a maximum rotating quantity N₁ counted for thetime in which it takes to stop for the motor MO from the rotatingcondition at the maximum speed by braking. Next, there also is provideda maximum rotating quantity N₂ of the motor MO counted for the time inwhich it takes to rotate at the maximum speed for the motor MO from thestop condition. Then in case the calculated rotating quantity Δn>N₁ +N₂=X₁, N₁ is set as the near focus zone Nzn. On the other hand, in caseΔn<N₁ +N₂, N₁ is set as Nzn. In this case. the motor MO is braked beforethe motor MO rotates at the maximum speed, therefore, after the rotationspeed of the motor MO reaches a low speed early, the lens is moved tothe focus position at the low speed. Therefore, it causes a problem inthat it takes a long time for the lens to reach the focus position,particularly in the condition that Δn approximates N₁. At the step No.151, in case the defocus count value Δn is more than X₁, the maximumvalue N₁ (X₁ >N₁) is set as the width Nzn of the near focus zone.Conversely, in case Δn is less than or equal to X₁, the value multipliedthe defocus count value Δn by "d" (d<1) is set as Nzn. At the step No.154, the comparison value, with the results the count value ZAFCmultiplied by "j" (j>1) is set as the width Nzw of the near zone usedfor catching up with the object. (Nzn<Nzw) Next, it is determinedwhether the focus flag AFIFF is "1" or not. In case the focus flag AFIFFis "1", the program flow goes to the step No. 156. On the other hand, incase the flag AFIFF is not "1", it is determined whether the first outflag FOF is "1" or not. In case the first out flag FOF is "1", theprogram flow goes to the step No. 156. In case the first out flag FOF isnot "1", the defocus count value Δn is set as the former defocus countvalue ΔnL. At the step No. 156, it is determined whether the high lighflag HLF is "1" or not, in case the flag HLF is not "1", the programflow goes to the step No. 159 without executing the steps No. 157through No. 160. Then the defocus count value Δn is set as the formerdefocus count value, the program flow goes to the step No. 164.

At the step No. 156, in case the high light flag HLF is "1", the programflow goes to the step No. 157. Then the difference between the formerdefocus count value ΔnL and the present defocus count value Δn, that is,the changed quantity Δ² n of the defocus count value is calculated.Next, at the step No. 158, it is determined whether the changed quantityΔ² n is less than a predetermined quantity L₁. In case Δ² n is less thanor equal to L₁, the program flow goes to the step No. 159 in the sameway of the case that the flag HLF has been reset. On the other hand, atthe step No. 158, in case the changed quantity Δn is more than thepredetermined quantity L₁, the program flow goes to the step No. 160.Then it is determined whether the first out flag FOF is "1", in case theflag FOF is not "1", the program flow goes to the step No. 161. The AFmicrocomputer MC₂ outputs the stop signal to the motor MO. the motorflag MOF is reset at the step No. 162, then the first out flag FOF isset and the program flow goes back to the step No. 36 in order tomeasure again. At the step No. 160, in case the first out flag FOF is"1", the program flow goes to the step No. 164. The above operation ofcalculating the changed quantity Δ² n and comparing Δ² n with thepredetermined quantity L₁ are performed in order to prevent fromresponding as a large defocus quantity when the large defocus quantityis suddenly calculated through an error on the condition of catching upwith the object.

At the step No. 164, the first out flag FOF is reset and also the focusflag AFIFF is reset. Next, at the step No. 165, it is determined whethera near zone flag NZF is "1". In case the near zone flag NZF is "1", theprogram flow goes to the step No. 170, on the other hand, in case thenear zone flag NZF is not "1", the program flow goes to the step No.166. The above determination of the near zone flag NZF is performed inorder to enlarge the range at which the motor MO rotates at a low speedduring the catching up mode after the lens has entered into the range ofthe near zone. Therefore, at the step No. 166, the defocus count valueΔn is compared with the narrower near zone count value Nzn, and at thestep No. 170 the defocus count value Δn is compared with the wider nearfocus zone count value Nzw. At the steps No. 166 or No. 170, in case itis determined that the defocus count value Δn is less than or equal tothe near zone count value Nzn or Nzw, the program flow goes to the stepNo. 167, then the near zone flag NZF is set. After that, the AFmicrocomputer MC₂ outputs "Low" to the terminal P₆ in order to make themotor control circuit MCC control so that the motor MO rotates at a lowspeed. At the step No. 159, the defocus count value Δn is loaded in thecounter and the program flow goes to the step No. 166. At the steps No.166 or No. 170, in case it is determined that the defocus count value Δnis more than the near zone count value Nzn or Nzw, the program flow goesto the step No. 171, then the near zone flag NZF is reset. Next, at thestep No. 172, the AF microcomputer MC₂ outputs "High" to the terminal P₆in order to make the motor control circuit MCC control so that the motorMO rotates at a high speed. At the step No. 173, the value subtractedthe near zone count value Nzn from the defocus count value Δn is loadedto the counter, and the program flow goes to the step No. 175. In FIG.10, the steps No. 175 through No. 182 are the operation performed whenthe lens is at the end position. At the step No. 175, it is determinedwhether a terminal flag TEF is "1" or not. In case the lens is not atthe end position, i.e. ∞ position, therefore the terminal flag TEF isnot "1", then the program flow goes to the step No. 183. On the otherhand, when the lens is at the end position, i.e. ∞ position, thereforethe terminal flag TEF is "1", then the program flow goes to the step No.176. At the step No. 176, the defocus direction is determined. In casethe image of the object is out of focus forward, the program flow goesto the step No. 177. On the other hand, in case the image of the objectis out of focus backward, the program flow goes to the step No. 178.Then in the both cases, a terminal position flag TPF is checked. Whenthe terminal position flag TPF is "1", the lens is at the nearest endposition to the object. On the other hand, when the terminal positionflag TPF is not "1", the lens is at the ∞ end position. At the step No.177, in case the terminal position flag TPF is not "1", the lens is atthe∞position and is in a front focus. Therefore, the lens cannot bemoved toward the body of the camera, the program flow goes to the stepNo. 180. In case the terminal position flag TPF is "1", the lens is atthe nearest end position to the object and is in a front focus, that is,the lens can be moved toward the body of the camera. Then the programflow goes to the step No. 179 in order to make the motor MO rotate. Onthe other hand, at the step No. 178, in case the terminal position flagTPF is "1", the lens is at the nearest end position to the object and isin a rear focus, the lens cannot be moved toward the object. Then theprogram flow goes to the step No. 180. In case the terminal positionflag TPF is not "1", when the lens is at the farthest end position fromthe object and is in a rear focus, the lens can be moved toward theobject. Then the program flow goes to the step No. 179. At the steps No.180 through No. 182, all the display of the focus condition and the outof focus condition is turned off, then the program flow goes back to thestep No. 36 in, order to measure again. At the step No. 179, theterminal flag is reset. Next, the motor flag MOF is checked at the stepNo. 183. In case the motor flag MOF is "1", when the motor has alreadybeen rotating, the program flow goes back to the step No. 36.

At the step No. 183, in case the motor flag MOF is not "1", when themotor MO stops, the motor flag MOF is set at the step No. 184. Next, atthe step No. 185, the defocus direction is determined. In case the lensis in a front focus, the program flow goes to the step No. 186. On theother hand, in case the lens is in a rear focus, then the program flowgoes to the step No. 188. At the step No. 186, the driving directionflag DDF is set. On the other hand, at the step No. 188, the drivingdirection flag DDF is reset. At the step No. 187 after the step No. 186,the AF microcomputer MC₂ outputs a "Low" signal to the terminal P₄. Onthe other hand, at the step No. 189 after the step No. 188, the AFmicrocomputer MC₂ outputs a "Low" signal to the terminal P₅. In theabove both cases, the AF microcomputer MC₂ makes the motor MO rotate inthe required direction. At the step No. 190 after the step No. 187 orNo. 189, the AF microcomputer MC₂ waits until the speed of the rotationof the motor MO attains predetermined stable speed, then the programflow goes back to the step No. 36.

The length of the wait time in the step No. 190 may be a predeterminedlength of time by considering the amount of the load of theinterchangeable lens and/or the drive voltage of the motor MO. In thestep No. 190, as a way of deciding whether or not the flow should go tothe step No. 36, the motor speed may be detected. Thus if it is detectedthat the motor speed reaches a predetermined value, the program flowgoes to the step No. 36.

The operation from the step No. 191 is the interruption to the interruptterminal it₃. The interruption to the interrupt terminal it₃ isperformed in order that the microcomputer MC₁ orders to start theshutter release motion to the AF microcomputer MC₂. After the AFmicrocomputer MC₂ receives the interrupt signal at the interruptterminal it₃, the program flow goes to the step No. 191. At the step No.191, it is determined whether the terminal P₁₂ is "High". In case theterminal P₁₂ is "High", when the single mode is selected, the programflow goes to the step No. 192. Then the AF microcomputer MC₂ outputs a"High" signal to the terminal P₈ in order to disable an in focusindicating buzzer. Next, at the step No. 193, the AF microcomputer MC₂outputs a "High" signal to the terminals P₄ and P₅ and makes the motorMO stop. At the step No. 194. the motor flag MOF is reset. Then the AFmicrocomputer MC₂ waits until the signal INREL becomes "High". In casethe signal INREL is "High", the program flow returns to the step No.148. At the step No. 191, in case the term:nal P₁₂ is "Low", under thenormal mode, the program flow goes to the step No. 196. Then the afterrelease flag AFRF is set, then the AF microcomputer MC₂ outputs a "Low"signal to the terminal P₂ in order to stop charging in the CCD at thestep No. 197. Then the display condition is stored in a memory at thestep No. 198, and at the step No. 199, the AF microcomputer MC₂ outputsthe "High" signals to the terminals P₇, P₈ and P₉ in order to turn thedisplay off. Next, at the step No. 200, the AF microcomputer MC₂ outputsa "High" signal to the terminal P₁₆ in order to cancel a demand QTRQ ofthe serial data communication. Then at the step No. 201, the serialinterruption is inhibited. The AF microcomputer MC₂ outputs a "High"signal to the terminal P₁₄ in order to inform it to the microcomputerMC₁ that the shutter release operation is permitted and the AFmicrocomputer MC₂ outputs "High" to the terminal P₁₃. At the step No.204, the timer of the AF microcomputer MC₂ is reset. Next, the AFmicrocomputer MC₂ makes the timer start and the AF microcomputer MC₂waits until the timer counts a predetermined time T₀. As soon as thetimer counts the predetermined time T₀, the AF microcomputer MC₂ outputsa "Low" signal to the terminal P₁ at a predetermined time in order thatthe interface circuit INF begins to charge in the CCD. When the releaseoperation of the shutter sets about, the shutter used for obstructingthe light is closed and the light does not reach the CCD sensor MLMC.Therefore, the above integral operation is to store the charge in theCCD corresponding to the dark output. The program flow goes to the stepNo. 208, as soon as the timer counts the time T₁, the program flow goesto the step No. 209. At the step No. 209, it is determined whether theexposure time value Tv for photographing is more than a threshold valueTvL. In case the exposure time value Tv for photographing is more thanTvL, the AF microcomputer MC₂ makes the motor rotate continuouslywithout stopping. Then the motor MO is made to stop when the motor MOrotates for the driven time and the counter interruption is receivedbecause the counter interruption is permitted. The routine of thecounter interruption will be described later. The threshold value TvL isset by such a value that the photograph by the exposure operation is notbadly influenced even though the exposure is made while the lens isbeing moved. At the step No. 209, in case the value Tv for photographingis less than or equal to the threshold value TvL, the program flow goesto the step No. 210. Then the driving signal to the motor MO is turnedoff in order to stop the motor MO. Besides, the timer value T₀ and T₁are set in order to make the first curtain of the shutter in the camerabegin to run (at the step #91 in FIG. 3) after the motor MO is actuallymade to stop by "High" driving signals RRT and LRT. Then the motor flagMOF is reset at the step No. 211. The program flow goes to the step No.212, the AF microcomputer MC₂ waits until the timer counts the time T₂.As soon as the timer counts the time T₂, at the step No. 213, the AFmicrocomputer MC₂ outputs a "Low" signal to the terminal P₂ at apredetermined time in order to stop to charge in the CCD in connectionwith the dark output. Then at the step No. 214, the CCD data of the darkoutput is read and stored in a memory. After that, the AF microcomputerMC₂ waits the interruption.

In FIG. 6, the operation from the step No. 216 is the interruption tothe interrupt terminal it₂, which is the AF stop interruption caused bythe microcomputer MC₁ As soon as the it₂ interruption is received, theprogram flow goes to the step No. 216. Then the driving signal to themotor MO is turned off in order to make the motor MO stop. Next, the AFmicrocomputer MC₂ outputs a "High" signal to the terminal P₇, P₈ and P₉and turn the display off. At the step No. 218, the AF microcomputer MC₂outputs a "High" signal to the terminal P₁₆ and the AF microcomputer MC₂cancels the demand of the serial data communication. The program flowgoes to the step No. 219, the AF microcomputer MC₂ outputs a "Low"signal (the signal INSTP) to the terminal P₂ for a predetermined timeand stop charging in the CCD. At the step No. 220, the interruption tothe terminals except for the interrupt terminal it₁ and it₂ isinhibited, and at the step No. 221, the AF microcomputer MC₂ outputs a"High" signal to the terminal P₁₄ in order to inform the microcomputerMC₁ that the operation of the automatic focal distance control iscompleted. At the step No. 222, the flags to be reset are reset, theprogram flow goes to the step No. 223, then the AF microcompute MC₂outputs a "Low" signal to the terminal P₁₃ and the program flow goes tothe power saving mode.

The routine of the counter interruption sets about from the step No. 241as shown in FIG. 11. As soon as the value counted down by each counterbecomes "0", the counter interruption sets about and the program flowgoes to the step No. 241. At the step No. 241, the driving signal to themotor MO is turned off. Next, at the step No. 242, the near zone flagNZF is checked. In case the flag NZF is not "1" the program flow goes tothe step No. 243 in order to change the rotation speed of the motor MOfrom a high speed to a low speed. At the step No. 243, the AFmicrocomputer MC₂ outputs a "Low" signal to the terminal P₆ and the AFmicrocomputer MC₂ makes the motor control circuit MCC control the motorMO at a low speed. Next, at the step No. 244, the near zone count valueNzn is loaded to the counter. Then at the step No. 245, the near zoneflag NZF is set. At the steps No. 246 through No. 248, the drivingdirection flag DDF is checked, then the AF microcomputer MC₂ outputs"Low" to the terminal P₄ or P₅ in accordance with the said direction inorder that the motor MO rotates in accordance with the said direction.The program flow returns.

At the step No. 242, in case the near zone flag is "1", when the motorMO has rotated for a required driving time, the program flow goes to thestep No. 249, then the motor flag MOF is reset. Next, at the step No.250, the AF focus flag AFIFF is set. Then at the step No. 251, it isdetermined whether the terminal P₁₂ is "High". In case the terminal P₁₂is "High", the program flow returns to the step No. 145 in order toperform the focus control operation in the single mode. On the otherhand, in case the terminal P₁₂ is "Low", under the single mode, theprogram flow goes to the step No. 252, then the after release flag AFRFis checked. In case the after release flag is "1", the program flowreturns. On the other hand, in case the after release flag AFRF is not"1", the program flow goes to the step No. 141 in order to perform thefocus control operation.

In FIG. 11, the operation from the step No. 253 is the subroutine usedfor detecting whether the lens is at the end position or not. First ofall, at the step No. 253, the content of the counter is inputted to aregister n'. At the step No. 254, a counter value Ln', which is storedin a memory at the last detection of whether the lens is at the endposition or not, is compared with the counter value n' inputted at theabove step No. 253. In case n' equals to Ln', when the encoder has notoutputted any pulse during detecting whether the lens is at the endposition or not, the program flow returns to the step No. 256 and theoperation on the condition that the lens is at the end position isperformed. On the other hand, in case n' is not equal to Ln', when thelens has not reached the end position, n' is stored as Ln' and theprogram flow returns to the former routine.

The operation from the step No. 256 is the operation on the conditionthat the lens has reached the end position. At the step No. 256, thedriving signal to the motor MO is turned off and the motor MO is made tostop. Next, at the step No. 257, a low contrast scan flag LCFI ischecked. In case the flag LCFI is not "1", when scanning with the lowcontrast is not performed, the program flow goes to the step No. 258.Then the terminal flag TEF is set, and the motor flag MOF is reset atthe step No. 259. Next, at the step No. 260, the driving direction flagDDF is checked. In case the flag DDF is "1", the program flow goes tothe step No. 261, then the terminal position flag TPF is reset and thelens is at the farthest end position from the object. On the other hand,in case the driving direction flag DDF is not "1", the program flow goesto the step No. 262, then the terminal position flag TPF is set andthereby it is indicated that the lens is at the nearest end position tothe object. Then the terminal P₁₂ is checked. In case the terminal P₁₂is "Low", under the single mode, the program flow goes to the step No.264, then the AF microcomputer MC₂ outputs a "High" signal to theterminals P₇ and P₉ and the display of the defocus direction is turnedoff. Then the program flow returns to the step No. 36 in order tomeasure the light again. On the other hand if, the terminal P₁₂ is"High", under the single mode, the program flow goes back to the stepNo. 36.

At the step No. 257, in case the low contrast scan flag LCFI is "1",when scanning with the low contrast is performed, the program flow goesto the step No. 265, then the low contrast flag LCF₂ is checked. In casethe low contrast flag LCF₂ is not "1", the program flow goes to the stepNo. 269 in order to scan conversely. Then the low contrast flag LCF₂ isset and the driving direction flag DDF is converted at the step No. 270so that the flag DDF becomes "0" when the flag DDF is "1" and the flagDDF becomes "1" when the flag DDF is "0". Next, at the steps No. 271through No. 273, the driving direction flag DDF is checked and the AFmicrocomputer MC₂ outputs the driving signal to the motor MO inaccordance with the said direction. Then the program flow goes back tothe step No. 36 in order to measure the light again. At the step No.265. in case the low contrast flag LCF₂ is "1", when scanning with thelow contrast is completed, the program flow goes to the step No. 266,then the low contrast flag LCF₃ is set and scanning with the lowcontrast is inhbited. At the step No. 267, the low contrast flags LCF₁and LCF₂ are reset, and at the step No. 268, the motor flag MOF is resetand thereby it is indicated that the motor stops. Then the program flowgoes back to the step No. 36 in order to measure again.

Moreover, in order that the control apparatus for the automatic focuscontrol is operated for itself for the check and adjustment during themanufacturing process in FIG. 1, the following steps is added to theabove flow charts of the AF microcomputer MC₂. In this case, the lenswith a particular fixed focal distance is mounted in order to check andadjust the control part for controlling the focal distanceautomatically. At the step No. 21, in case the flag AFRF is "1", it isdetermined whether the terminal P₁₂ is "High" or not. In case theterminal P₁₂ is "Low", the program flow goes to the step No. 27. On theother hand, the terminal P₁₂ is "High", when the check mode has beenselected, the program flow goes back to the step No. 36. Then at thestep No. 52, it is determined that the terminal P₁₂ is "High", and it isdetermined whether the input and output port P₇ is in the input mode orthe output mode. In case the input and output port P₇ is in the inputmode, when the single mode shown in FIG. 5 has been selected, theprogram flow goes to the step No. 54. On the other hand, in case theinput and output port P₇ is in the output mode, the circuit shown inFIG. 1 is in the check mode and the information is fixedly stored in theROMs in the microcomputers MC₁ and MC₂. The conversion factor of theabove particular lens is set for calculating and the program flow goesto the step No. 60. Moreover, at the step No. 139, it is determined that"High" is inputted to the terminal P₁₂ ' and it is determined whetherthe terminal P₇ is in the input mode or the output mode. In case theterminal P₇ is in the input mode, when the single mode has beenselected, the program flow goes to the step No. 145. On the other hand,in case the terminal P₇ is in the output mode, the program flow goes tothe step No. 141.

By adding the above steps and inputting a start signal of the AFoperation, even though the circuit is so arranged as shown in FIG. 1,the AF microcomputer MC₂ operates for itself having no relation with themicrocomputer MC₁ and the control part for the automatic focus controlcan be operated for itself for the check and adjustment of the controlpart. Moreover, at the step No. 52, it is determined that the terminalP₁₂ is "High" and the terminal P₇ are in the output mode, the data ofthe CCD is outputted from input and output ports not shown or the outputterminal of the serial data. Next, the data used for adjusting are readand the program flow goes to the step No. 60. If the focus quantity Δεis outputted for checking and adjusting the control circuit after thestep No. 60 is performed and the terminal P₇ is made to be in the outputmode, it may be easy to check and adjust the control circuit.

Although the AF microcomputer MC₂ is set about only under the FA modewhen the switches TSS, ASS, ISS MOSS, UPS and DOS are operated in thesteps #4 through #11 in FIG. 2, in place of this method, the followingoperation may be employed. Namely, the AF microcomputer MC₂ is alwaysset about simultaneous with the start of the control microcomputer MC₁but the lens is not driven so far as the one of the switches TSS, ASS,ISS, MOSS, UPS and DOS causes to start the microcomputer MC₁ in the AFmode. In addition, when the camera is set in the operative condition bythe operation of the those set switches under AF mode, it is possible toenable the display as in the FA mode.

Also in the step No. 86 when the reset of the low contrast flag CF₁ isdetected, the program flow may be shifted to the step No. 36 omittingthe steps Nos. 87 to 92. According to this arrangement, the photographiclens may be moved up to the in focus position (referred to a first infocus position) based on the data just before the change of the contrasteven though the contrast of the object is suddenly changed to the lowcontrast, and in case the contrast measured by the camera is restored tothe initial value before the photographic lens reaches the first infocus position, the lens may be moved up to in focus position inaccordance with a new data obtained based on the restored contrast.However in case the contrast is not restored i.e., the low contrast iscontinued before the photographic lens reaches the first in focusposition, the photographic lens is moved up to the first in focusposition.

Table 5 represents the relation signals and their contents in the AFmicrocomputer MC₂ ' while Table 6 represents the contents of flagsreferred to in the flow program shown in FIGS. 6 through 11.

                                      TABLE 5                                     __________________________________________________________________________    The signals in the AF microcomputer MC2                                       Port in                                                                       micro-                                                                             Normal (camera) mode           Single (lens itself) mode                 computer                                                                           Signal                                                                             Content              Signal                                                                             Content                                   __________________________________________________________________________    P.sub.0                                                                            INEN the integral completion signal                                                                     INEN the integral signal completion                                                signal                                              from the interface circuit INF                                                                          from the interface circuit INF            P.sub.1                                                                            INSTA                                                                              the integral start signal                                                                          INSTA                                                                              the integral start signal                           to the interface circuit INF                                                                            to the interface circuit INF              P.sub.2                                                                            INSTP                                                                              the integral stop signal                                                                           INSTP                                                                              the integral stop signal                            to the interface circuit INF                                                                            to the interface circuit INF              P.sub.3                                                                            ADEN the A/D conversion data input timing signal                                                        ADEN the A/D conversion data input timing                                          signal                                              from the interface circuit INF                                                                          from the interface circuit INF            D.sub.0                                                                            ADD  the input bus for the CCD output                                                                   ADD  the input bus for the CCD output                    from the interface circuit INF                                                                          from the interface circuit INF            P.sub.4                                                                            RRT  the clockwise rotation signal                                                                      RRT  the clockwise rotation signal                       to the motor driving circuit MCC                                                                        to the motor driving circuit MCC          P.sub.5                                                                            LRT  the counterclockwise rotation signal                                                               LRT  the counterclockwise rotation signal                to the motor driving circuit MCC                                                                        to the motor driving circuit MCC          P.sub.6                                                                            GOV  the speed switching signal                                                                         GOV  the speed switching signal                          to the motor driving circuit MCC                                                                        to the motor driving circuit MCC          P.sub.8                                                                            IFLS the driving signal to the light emitting                                                           IFBZ the driving signal to the buzzer                    diode for displaying the in focus condition                                                             for displaying the in focus                                                   condition                                 P.sub.12                                                                           SNS  the single/normal mode switching signal                                                            SNS  the single/normal mode switching                                              signal                                    P.sub.7                                                                            RFLS the driving signal to the LED for displaying                                                            the input bit of defocus quantity-                  the defocus direction in a rear focus                                                                   encoder pulse count conversion                                                factor                                    P.sub.9                                                                            FFLS the driving signal to the LED for displaying                                                            the input bit of defocus quantity-                  the defocus direction in a front focus                                                                  encoder pulse count conversion                                                factor                                    P.sub.10                                                                           FLS  the focus lock signal     the input bit of defocus quantity                                             encoder pulse count conversion                                                factor                                    P.sub.11                                                                           AMS  the AF/FA mode switching signal                                                                         the input bit of defocus quantity-                                            encoder pulse count conversion                                                factor                                    P.sub.13                                                                           STPOK                                                                              the clock pulse stop signal                                                                             the input of defocus quantity                       to the microcomputer MC.sub.1                                                                           encoder pulse count conversion                                                factor                                    P.sub.14                                                                           AFEN the AF completion signal  the input bit of defocus quantity-                  to the microcomputer MC.sub.1                                                                           encoder pulse count conversion                                                factor                                    P.sub.15                            the input bit of defocus quantity-                                            encoder pulse count conversion                                                factor                                    P.sub.16                                                                           DTRQ the demand signal of the serial                                                                         the input bit of defocus quantity-                  communication to the microcomputer MC.sub.1                                                             encoder pulse count conversion                                                factor                                    CLI.sub.0                                                                          ENCL the encoder output pulse signal                                                                    ENCL the encoder output pulse signal                     from the encoder circuit ENCC                                                                           from the encoder circuit ENCC             it.sub.1                                                                           AFSTA                                                                              the AF start interruption signal                                                                        not use                                             from the microcomputer MC.sub.1                                     it.sub.2                                                                           AFSTP                                                                              the AF stop interruption signal                                                                         not use                                             from the microcomputer MC.sub.1                                     it.sub.3                                                                           INREL                                                                              the release interruption signal                                                                    INREL                                                                              the release interruption signal                     from the microcomputer MC.sub.1                                                                         from the microcomputer MC.sub.1           SICK.sub.0                                                                         SICK the clock pulse for the serial communication                                                            not use                                             from the microcomputer MC.sub.1                                     SIIN.sub.0                                                                         SIBS.sub.1                                                                         the serial data           not use                                             from the microcomputer MC.sub.1                                     STCLIN                                                                             STCL the driving clock pulse                                                                            STCL the driving clock pulse                             to the AF microcomputer MC.sub.2                                                                        to the AF microcomputer                   __________________________________________________________________________                                        MC.sub.2                              

                                      TABLE 6                                     __________________________________________________________________________    The flag used in the flow charts                                              Flag code                                                                           Name of flag                                                                             Content         "0" state "1" state                          __________________________________________________________________________    FMF   Focus mode flag                                                                          distinction of the AF or FA mode                                                              the AF mode                                                                             the FA mode                        FLF   Focus lock flag                                                                          determination of the focus                                                                    not on the focus                                                                        on the focus lock                                   lock condition  lock condition                                                                          condition                          MOF   Motor flag if the motor is rotating                                                                      motor stop                                                                              motor rotating                     LCF.sub.0                                                                           Low contrast flag 0                                                                      if the object has the low contrast                                                            normal condition                                                                        low contrast                       LCF.sub.1                                                                           Low contrast flag 1                                                                      if scanning with the low                                                                      not scanning                                                                            scanning                                            contrast is performed                                        LCF.sub.2                                                                           Low contrast flag 2                                                                      if forward or backward scanning                                                               forward scanning                                                                        backward scanning                                   is performed                                                 LCF.sub.3                                                                           Low contrast flag 3                                                                      inhibition of scanning with the                                                               permission of                                                                           inhibition of                                       low contrast    scanning  scanning                           AFRF  After release flag                                                                       if the release operation                                                                      not performed                                                                           performed                                           is performed                                                 LLF   Low light flag                                                                           if the object has low brightness                                                              normal condition                                                                        low brightness                     AFIFF AF in focus flag                                                                         if the image of the object is in                                                              out of focus                                                                            in focus                                            focus in the AF mode                                         DDF   Driving direction flag                                                                   the driving direction                                                                         toward the object                                                                       toward the body of                                                            the camera                         FOF   First out flag                                                                           if the sudden big change in the                                                               normal condition                                                                        sudden big change                                   the defocus value occurs                                     NZF   Near zone flag                                                                           if the lens is inside or outside                                                              outside of the                                                                          inside of the                                       of the near zone                                                                              near zone near zone                          TEF   Terminal flag                                                                            if the lens is at the end postion                                                             not at the end                                                                          at the end position                                                 position                                     TPF   Terminal position flag                                                                   the side of end position of                                                                   ∞ focus side                                                                      closest focus side                                  the lens                                                     HLF   High light flag                                                                          if the object has high brightness                                                             not high brightness                                                                     high brightness                    __________________________________________________________________________

What is claimed is:
 1. An automatic focus control cameracomprising:means for obtaining information necessary for auotmatic focuscontrol; means for providing a driving power of focus adjustment inaccordance with the information; means for directing said obtainingmeans to operate; means for starting a camera exposure operation, saidexposure operation taking a time period from an initiation of the campraexposure operation until an initiation of the actual exposure of thefilm, and means for interrupting said providing means from providing thedriving power when the actual exposure of the film is taking place,whereby said providing means is allowed to continue the provision of thedriving power after the initiation of the camera exposure operationuntil the actual exposure of the film is initiated.
 2. An automaticfocus control camera comprising:means for obtaining informationnecessary for automatic focus control; means for providing a drivingpower of focus adjustment in accordance with the information; means fordirecting said obtaining means to operate; means for starting a cameraexposure operation, said exposure operation taking a time period from aninitiation of the camera exposure operation until an initiation of theactual exposure of a film; means for interrupting said providing meansfrom providing the driving power when the actual exposure of the film istaking place, whereby said providing means is allowed to continue theprovision of the driving power after the initiation of the cameraexposure operation until the actual exposure of the film is initiated;means for detecting whether an exposure time for the exposure operationis shorter than a predetermined value, and means responsive to saiddetecting means for disabling said interrupting means to allow thecontinuation of the driving power during the actual exposure when theexposure time is shorter than the predetermined value.
 3. An automaticfocus control camera comprising:means for obtaining informationnecessary for automatic focus control; means for providing focusadjustment in accordance with the information; means for starting acamera exposure operation; means for interrupting said providing meansfrom providing focus adjustment when the actual exposure of a film istaking place, whereby said providing means is allowed to continue theprovision of focus adjustment after the initiation of the cameraexposure operation until the actual exposure of the film is initiated;means for detecting whether an exposure time for the exposure operationis shorter than a predetermined value, and means responsive to saiddetecting means for disabling said interrupting means to allow thecontinuation of the focus adjustment during the actual exposure when theexposure time is shorter than the predetermined value.
 4. An automaticfocus control camera comprising:a shutter release button capable ofresponding to two manual operations that can be applied in the order ofa first and a second operation; a signal output means for outputting afirst and a second signal in response to the first and second manualoperation of said shutter release button, respetively; an objectivelens; a focus condition detecting means for detecting a focus conditionof said objective lens; a driving means for driving said objective lenstowards an in-focus position in accordance with the result of the focuscondition detection; means responsive to the second signal for startinga camera exposure operation from the start of which an actual exposureoperation is initiated after the lapse of a predetermined time, and acontrol means for starting the operations of said detecting means andsaid driving means in response to the first signal, and maintaining thelens driving operation of said driving means when said detecting meansdoes not detect an in-focus condition at the start of the cameraexposure operation.
 5. An automatic focus control camera according toclaim 4, wherein said control means stops the lens driving operation ofsaid driving means when an actual exposure operation is initiated.
 6. Anautomatic focus control camera comprising:means for obtaininginformation necessary for automatic focus control; an objective lens;means for driving said objective lens in accordance with theinformation; means for starting a camera exposure operation, saidexposure operation taking a time period form the start of the cameraexposure operation until an initiation of the actual exposure of thefilm; first means for terminating the lens driving operation of saiddriving means when said objective lens is reached to an in-focusposition irrespective of whether or not the actual exposure operation istaking place, and second means for terminating the lens drivingoperation of said driving means before the initiation of the actualexposure operation.
 7. An automatic focus control cameracomprising:means for obtaining information necessary for automatic focuscontrol; an objective lens; means for driving said objective lens inaccordance with the information and terminating the lens drivingoperation thereof when said objective lens is reached to an in-focusposition; means for starting a camera exposure operation, said exposureoperation taking a time period from the start of the camera exposureoperation until an initiation of the actual exposure of the film, andcontrol means for maintaining the lens driving operation when saidobjective lens is not reached to an in-focus position even if the cameraexposure operation has started and terminating the lens drivingoperation before the initiation of the actual exposure operation.
 8. Anautomatic focus control camera comprising:means for obtaininginformation necessary for automatic focus control; an objective lens;means for driving said objective lens in accordance with the informationand terminating the lens driving operation thereof when said objectivelens reaches an in-focus position; said driving means being selectivelyoperable in a first operation mode and a second operation mode; meansfor outputting a signal representative of an exposure time; means forstarting a camera exposure operation, said exposure operation taking atime period from the start of the camera exposure operation until aninitiation of the actual exposure of the film; means for controlling theactual exposure time in accordance with the signal from said outputtingmeans, and means for changing the lens driving operation of said drivingmeans in accordance with the signal from said outputting means so as toselect the first operating mode when the signal representative of theexposure time is shorter than a predetermined exposure time, and thesecond operating mode when the signal representative of the exposuretime is equal to or longer than the predetermined exposure time.
 9. Anautomatic focus control camera according to claim 8, further comprisingmeans for maintaining the lens driving operation when said objectivelens is not reached to an in-focus position even after the start of thecamera exposure operation, said maintaining means terminating in thefirst operating mode the lens driving operation before the initiation ofthe actual exposure operation, and maintaining in the second operatingmode the lens driving operation even during the actual exposureoperation when said objective lens is not reached to an in-focusposition.
 10. An automatic focus control camera comprising:means forobtaining information necessary for automatic focus control; anobjective lens; means for driving said objective lens in accordance withthe information and terminating the lens driving operation thereof whensaid objective lens reache s as in-focus position; means for outputtinga signal representative of an exposure time; means for starting a cameraexposure operation, said exposure operation taking a time period fromthe start of the camera exposure operation until an initiation of theactual exposure of the film; means for maintaining the lens drivingoperation when said objective lens has not reached an in-focus positioneven after the start of the camera exposure operation; means forcontrolling the actual exposure time in accordance with the signal fromsaid outputting means, and means for changing the lens driving operationof said driving means, said driving means being selectively operable indifferent operating modes of a first operating mode and a secondoperating mode.
 11. An automatic focus control camera according to claim10, wherein said changing means sele cts the first operating mode whenthe signal representative of the exposure time is shorter than apredetermined exposure time, and selects the second operating more whenthe signal representative of the exposure time is equal to or longerthan the predetermined exposure time.
 12. An automatic focus controlcamera according to claim 11, wherein said maintaining means terminates,in the first operating mode, the lens driving operation before theinitiation of the actual exposure operation, and maintains, in thesecond operating mode, the lens driving operation even during the actualexposure operation when said objective lens has not reached as in-focusposition.